AUTO-DOSING, STREAMING WATER CHANGE, AND TESTING

Paul G

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I have been experimenting with a new approach to planted tank management over the last couple of years and I would like to share it here. This will take the form of a journal in the usual sense, but it describes methods and novel protocols that, while not unheard of, do not seem to be widely practiced. While I unabashedly claim unqualified success, I will refrain from advocacy entirely, as my approach would certainly be, admittedly, not to everyone's liking. It involves automation technology, multi-parameter data-logging, and frequent testing. Much of the operational philosophy concerns coordinated fertilization and water-change strategies. I offer below, without discussion, a few graphics as a foretaste of what will be presented. If there isn't much interest, I will not continue, but I very much hope to stimulate some dialogue.

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Lmuhlen

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Please do continue, I much enjoy some automation.

But it seems like a lot of effort for what looks like a tank with low-demanding plants, which would probably thrive even under unfavorable conditions.

Give us some explanation on what is what in your charts, please. You have 2 water changes per day and on average a 12h photoperiod?
 

Paul G

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The 7-day graph illustrates the diurnal cycles of the ORP (redox) and the dissolved oxygen (DO). There is much more to be said about this. Note that the DO regularly reaches supersaturation. This is an index of the rate of carbon fixation under these lights and is entirely under control of the plants. Aeration by air pump is set to come on when DO falls below 5.5 ppm, establishing a minimum allowed oxygen tension. This occurs generally as a response to the spike in COD (chemical oxygen demand) which occurs immediately upon the morning dosing, which is also exhibited by the notch in the redox trace.

These round charts are 24 hour clocks. The lighting schedule viewed in connection with the lighting system diagram indicates the timer functions programmed into the Apex Aquacontroller. All the Kessils and the BML (Build My LED) strips have ramped dimming, also programmed into the Apex.

ODEs (open drain events) occur on the hour fourteen times per day. It has been determined that when the tank circulation is operating normally, each ODE, timed at 90 seconds ON, drains 3.375 liters and the ATO immediately tops this off from the RO/DI reservoir. Total daily demand on the RO/DI supply is 47.25 liters, or 12.5 gallons. The Apex Aquacontroller thus emulates a continuous water change. Parcelling the water change by means of timed ODEs is a practical way of achieving reliable volumetric regulation, as the Apex is monitoring and controlling the waterline with optical sensors and solenoid valves. I refer to this as a Streaming Water Change Regimen, SWCR.

Larger water changes are performed on an ad hoc basis only.

It is necessary to automatically adjust the water chemistry at a rate that is calibrated to correspond with the continuing dilution of the SWCR. This has required experimentation with dosing pump timers and involved an intensive testing regime. It should be clear that the method is by necessity automated.

Potassium is supplied for luxury uptake concentrations. Main-source potassium and buffer are provided as K2CO3 three times daily. Dose rate maintains +K at circa 40 ppm, and KH at between 7 and 8 degrees.

This is a softwater environment. General hardness reconstitution and some additional buffer are provided by an earth-alkali carbonate reactor in one of the filter loops. Continuous equilibration with the SWCR maintains GH at circa 3 degrees. Aragonite, as crushed shell/coral, works for this, but I am currently experimenting with SeaChem Reef Reactor to see if a more favorable Ca:Mg ratio will result. At present, ++Ca is ca 40 ppm and ++Mg is ca 15 ppm. Calibration of this is a function of the total amount of medium in the reactor and the flow rate through the filter (consistently not less than 110 gph), something I am in the process of fine tuning now. I am able to supply MgSO4 and CaCl2 on an ad hoc basis, but this has been unnecessary for a while now.

Nitrate and phosphate are autochthonous, arising from environmental metabolism, i.e. fish food and all other macromolecular sources. I am attempting to achieve continuous equilibration with the SWCR to maintain strict oligotrophy. As a rule, typical values are ca 2 ppm NO3, and ca 0.5 ppm PO4. I currently dose very small quantities of KNO3 and KH2PO4 daily to prevent drift of these concentrations to 0.

I use SeaChem Flourish Comprehensive and Flourish Trace for all micros. All iron is supplied as ferrous gluconate only, and the dose rate for Flourish is adjusted such that iron averages between 0.1 and 0.2 ppm (test performed within one hour of early AM dose).

All inorganic compound solutions are prepared 100 grams/liter distilled water. The dose rate of the supplement is metered by dosing pump run time, not concentration of solution. Supplement dosing can easily be adjusted by simple program line amendments in the pump timers.

There is a good deal more to be described. Coming up, with pictures.

I would not regard the hardiness of the plant as a criterion for the quality of its care. This whole system is intrinsically automatic, and while I have gone to a good deal of trouble and expense to set it up, it now basically runs itself. I just feed this thing. Had it not exhibited proof of concept, I would not be presenting it here and now. It's not a method for everyone, but it works.
 
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Paul G

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Nymphaea lotus v rubra

Today's numbers

pH: 6.7
ORP: 459 mV
NO3: 0
PO4: 0.12 ppm
Fe: 0.10 ppm
K: 40 ppm
dGH: 4.2
Ca: 56 ppm
Mg: 20 ppm
dKH: 7.7

Over the last ten days I have been feeding the fish less generously than usual. I keep a running plot of nutrient parameters (test results), and compare these with feeding patterns. There is an apparent general correspondence to the NO3 and PO4 concentrations. I typically feed very generously and often, and usually am able to get NO3 to persist at around 2 ppm. Orthophosphate very seldom tests over 0.5 ppm. The aim is to hold NO3 and PO4 to these low numbers, but always non-zero. This tank is densely planted; there are no macronutrient deficiencies and growth is rapid. Nitrate has been dwelling at 0 for a few days. The SWCR is outrunning nutrient evolution and the small supplementation currently programmed. So I am resuming the usual heavy feeding.

The SWCR is not outrunning the GH reconstitution. The ++Ca is inclining quickly. Today I will halve the reactor medium load and slow the flow rate a little.

I should explain the circulatory system. This is a 210 gallon glass tank, 72 W x 30 H x 24 D. Accounting inexactly for substrate and hardscape materials, I call this a 200 gallon aquarium. The total turnover rate is 5 to 6 times per hour, depending on filter conditions, using three Iwaki MD55RLT pumps. Water is polished to 25 microns. Flow rates in GPH are monitored on all four returns. The high-speed loops use 100 micron cartridges, usually without core media. The processing loops each use 100 micron followed by 25 micron cartridges. These are where media and temperature control are installed, and each loop has an in-line CO2 diffuser, one of which is shown in the last photo below.

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Paul G

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Cryptocoryne wendtii & Microsorum pteropus

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Cryptocoryne wendtii

Today's numbers

pH: 6.7
ORP: 464 mV
NO3: 1 ppm
PO4: 0.06 ppm
Fe: 0.10
K: 40 ppm
dGH: 3.7
Ca/Mg: 52/14 ppm
dKH: 6.8

If "jungle" is a defined specific style of aquarium, this one is that. I do prefer hardy and fast-growing plants, and my philosophy is to let the plants have their way. More than indulging a decorative impulse, observing natural spontaneity is what I enjoy about this effort. I like a wild 'scape. But not manicured does not mean not managed. I do trim the plants to relieve congestion, since overcrowding cuts off the light to the understory. This is something easily seen in the DO trace as the lower growth O2 evolution is impeded in the shade. The Echinodorus and the Nymphaea are the keystone species in this ecosystem but their leaves, growing very large near, and on, the surface must be trimmed. Usually picking out the older, tattier leaves is sufficient to open up the space. The Sagittaria subulata spreads fairly rapidly by runners and its density must be controlled by pulling it out by the roots.

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Allwissend

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Thank you for the very detailed posts on your setup. I am sure some people looking for a similar setup will be inspired. The fish seem to be having a good time in there.

Looking through your posts, the Ca solution (?) seems to have a lot of precipitate settling at the bottom despite being on a magnetic stirrer. I would suggest moving to CaCl2 as it has a higher solubility and thus you will be able to dose better. Don't mix it with MgSO4 though.

The figures for GH and Mg and Ca seem off by quite a lot. For example 52 mg/L Ca alone will give you 7+ °dH in GH, yet the tests only report 3.7 °dH. Both cannot be right. As you want very specific values in your tank it might be worth looking into which one gives a more accurate value using standardized solutions.
 
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Paul G

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Your conversion factor for mg/L (ppm) to dGH is 7.4. That's a new one for me. I use 17.9. Some places I think I've seen 17.8 used. If we are talking conversions to German hardness scales, I believe 17.9 is correct for both earth-alkali to GH and CO3 to KH. You can find this math any number of places, but just Google "ppm to gh" and you'll get a dozen.

There is often some sedimentation in a quiescent body, but compounds that have high water solubility rapidly diffuse when stirred. In some of the dosing vats, there is some crystallization along the walls, especially as the fluid level drops, but these don't remain. Also I had been using CaCl2; CaSO4 does not work in this type of doser due to its difficulty in water solubility. It forms a sludgy sediment and clogs the lines.

But as I discussed, I am not routinely dosing Ca or Mg in prepared solutions.

I am using a different method of GH reconstitution, and the Ca:Mg concentrations are working out pretty well. Just now I am fine tuning the rate through the reactor to balance the SWCR. I have not dosed any chloride or sulfate solutions to provide earth-alkalis for months. I only keep this doser in standby so as to conveniently provide an extra shot of MgSO4 on an ad hoc basis to maintain a desirable Ca:Mg ratio, but I haven't needed to do that since I switched from aragonite to Reef Reactor. This experiment is not fully concluded, but it's looking like it will be working as hoped.

On a related point: I have tried using DIY micronutrient/trace mixes in my auto-doser system and always got solutions that were prone to sedimentation and clogging. After switching to SeaChem Flourish I have had none of that.
 

Paul G

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Perhaps I should show the way the doser system looks now. The above picture is from long ago and I won't try to describe what I think you see in it. The photo below is the current state of the rig as it has been for at least a year. Mea culpa; appearances can deceive.

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Lmuhlen

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From what I gathered, 17,8 ppm of CaCO3 or 10ppm of CaO equals 1 dGH. If you are measuring only the concentration of Ca ions, you would have to adjust to the roughly 7 ppm per dGH.
 
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Allwissend

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That is likely the source of error. Indeed, hardness can often be presented by hobby grade kits as ppm CaCO3. The CaCO3 part is often left out. The conversion between ppm CaCO3 and °dH is as Lmuhlen said 17.8, and only applies once you figured out the equivalent CaCO3 conc.

Code:
(mg/L Ca) * 2.5 * Ca+(mg/L Mg) * 4.1 = (ppm CaCO3 GH)

or for a quicker route to German degrees

Code:
(mg/L Ca)  * 0.14 + (mg/L Mg) * 0.23 = (°dH GH )

If the measured concentration for Ca and Mg are correct than the GH is 10.5°dH.

The second pic of the dosing unit looks much cleaner. What pH did you adjust your previous trace mix to ? Do you have any idea why you observed precipitation ?
 
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Paul G

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The general hardness is not a measure of CaCO3 or any other compound. It is a measure of all the ions of the earth-alkali elements comprising Group 2 of the periodic table. For practical considerations, in aquarium water chemistry, these are principally ++Ca and ++Mg. Tests for ppm, or mg/L, of Ca or Mg or of Ca + Mg (which is GH) are testing the presence of these ions, they are not quantitative analyses of molar concentrations of a compound. Test GH, you get total Ca + Mg. Test Ca. Difference is Mg. These are ions of bivalent light metals being tested. Likewise, tests for KH are testing bicarbonate, -HCO3, or carbonate, --CO3 ions, not for molar concentrations of carbonate salts.
 

Paul G

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What precipitation are you referring to? Don't recall mentioning it. All solutions dispense as well-mixed fluids.

The ppm CO2 is a function of KH and pH. There is a well-known chart that shows ppm CO2 for every pH at every dKH. Sources of acidity other than CO2 throw the chart off, and it's completely useless if there is a lot of humus, tannins, etc, as in blackwater biotopes.

Since I use a pH controller, I can program the target pH, and since I know by test what the KH is, and I know I don't have significant other sources of acid, I then know my CO2 in ppm.
I hold the dKH around 7 as a rule, and Apex controls the CO2 solenoid by enforcing the programmed pH, which is currently 6.7. Carbon dioxide concentration in the jungle just now is approximately 40 ppm, certainly 30 ppm at least. If I increased buffer dose rate to establish dKH = 8, the CO2 ppm would go up around another 10 ppm, with no change in the pH.

The SeaChem Flourish Trace mix or any other substance being dosed, has no effect on the pH. Without the pH controller, the only dosed fluid that would have any effect on pH would be the buffer. But the Apex Aquacontroller holds the running average pH at a solid 6.7 at all times.

With this set of conditions, this 200 gallon aquarium uses a 20 lb cylinder of CO2 about every 40 days.
 

Lmuhlen

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The general hardness measure is a measure of ions of group 2 elements, but the units for measuring them were based on the addition of salts, so they are usually referrenced to the addition of common salts. The german scale, dGH, is based on the addition of CaO and the relation was established as 10 ppm of CaO adding 1 dGH. If you do the molecular weight arithmetics, you can create a reference for how many ppm of CaCO3 you need for 1 dGH, and that became one of the standard scales for test kits in the hobby, that assumes that 17.8 ppm -> 1 dGH. But if you are measuring Ca and Mg ions concentration, not CaCO3 concentration, you can't use the 17.8 value.

If your Calcium test is already giving results in ppm of CaCO3 equivalent, then your calculations are correct, you would just need to make note of the correct unit.
 
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Allwissend

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well i mean test for mg/L Ca or test for mg/L are quantitative analyses for a specific compound (it's not a present/absent test), but that is beside the point.

The formulae above help you figure out the general hardness of water if you create a solution of known Ca and Mg concentration. General hardness can be expressed in several equivalent units, one way is °dH - German degrees , another one is ppm CaCO3 etc. When general hardness is expressed using ppm CaCO3 as units it obviously does not mean your water has that concentration of CaCO3. It means that if that many milligrams of CaCO3 were fully dissolved in 1 L of pure water the solution created will have an equivalent general hardness to the general hardness in your aquarium." If you are curious, historically 1 °dH was defined as being equivalent to 10 mg/L CaO... this again does not mean that suddenly your aquarium water has that concentration of CaO when you express general hardness as °dH. The ppm unit there does not stand for bivalent metals per million parts of water.

This is not a valid way to figure out Mg.
Code:
3.7 * 17.8 = 65.86
65.86 - 52 = 14

dGH: 3.7
Ca/Mg: 52/14 ppm
You need to convert Ca to equivalent CaCO3 mass concentration. 52 * 100 / 40 = 52 * 2.5 = 130 equivalent CaCO3 conc.

52 mg/L Ca will already put you at 7+ °dH. Try it out with a known solution of either Ca or Mg and a fresh GH test.


What precipitation are you referring to? Don't recall mentioning it. All solutions dispense as well-mixed fluids.

This :

On a related point: I have tried using DIY micronutrient/trace mixes in my auto-doser system and always got solutions that were prone to sedimentation and clogging. After switching to SeaChem Flourish I have had none of that.
My question was also specifically regarding the pH of the trace mix.
 

Paul G

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I indicated that I had sedimentation (not specifically precipitation) issues with DIY micronutrient mixes. I think a few of the ingredients in the couple I tried were soluble with difficulty and needed a lot of stirring, but clogged the lines easily. The system just didn't get along with these mixes and I got sketchy performance and sometimes messes. Flourish does not have this issue. If there is any minor sedimentation, it is easily dispersed by the stirrer prior to being dispensed.

I don't know what the actual pH is of the additive itself. SeaChem Flourish Comprehensive is added 17 ml per day, and Flourish Trace is added 1.5 ml per day. Since there is absolutely no impact to the pH in the tank water, I have not been interested to know these values. If you would like to know the pH of SeaChem Flourish Trace, I can do the test.

On the hardness issue: I accede to your point about what is actually being measured. You are correct. Molar concentrations are different due to the difference in Ca and Mg mass, and the test is designed to give the result as CaCO3 equivalent. The LaMotte GH test kit gives all the results in ppm CaCO3. It is two tests, one is for total hardness, giving the contribution of both MgCO3 (expressed as CaCO3) and CaCO3, and one is for CaCO3 alone.

The instruction specifically states that MgCO3, expressed as CaCO3 equivalent, is the difference between the tests. The numbers I report for both Ca and Mg are specified per the test designer's documentation. The maker of the test expressly instructs me to do this. Thus, my LaMotte kit gives me a Ca:Mg ratio that represents the relationship with sufficient reliability that I can use that information to make decisions concerning dose rates, etc.

Since these parameters are already expressed as CaCO3 eq no further conversion to find the equivalency is done. Same goes for the Hanna photocolorimeter I use for alkalinity. The test gives KH in ppm CaCO3 eq.

Every units converter and every discussion on this topic I can locate give the conversion for both dGH and dKH as:

German degree = ppm CaCO3 / 17.85

ppm CaCO3 = German degree x 0.056

This is the conversion I will use. Thus, the 66 ppm total GH yielded by my LaMotte kit is 3.7 degrees German.

I admit my earlier post about what is actually being measured is in error. Having stipulated that the ppm numbers being reported in all cases are CaCO3 equivalent, I believe I can nevertheless surely rely on their relative significance in terms of the parameters under consideration. They are not ionic concentrations, but do convey the information being sought. If this is essentially a question of specifying units of measure, that is a distinction without a difference. I will not, as a practical matter, qualify every reference made to ppm hardness as being expressed as CaCO3 eq.
 

Paul G

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Now I get your question! About the pH of the earlier DIY micro solutions: I have no idea, but I used distilled water, so likely circumneutral pH without adding vinegar. With the fouling of the lines, I was just not inclined to experiment. The SeaChem products are doing the job, so I'm good.
 

Paul G

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Today's numbers

pH: 6.7
ORP: 494 mV
NO3: 1 ppm
PO4: 0.07 ppm
Fe: 0.12 ppm
K: 35 ppm
GH: 3.1
Ca/Mg: 48/12 ppm
KH: 7.2


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The above 7-day graph is the DO trace plotted with the light energy input. Amp_35 is total amps at 120VAC being drawn by all the light's power supplies simultaneously. Energy input to the lights rises daily from 0 to 420 watts. The slight drop-off of peak DO over the last two days is indicative of congestion and the need to prune overgrowth so that the light can penetrate the jungle.

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Above graph is a typical brightness control plot. This is DADU (DAWN/DUSK) which is the four Kessil A80 Suns. Amplitude figures are percent of total lamp capacity. The Apex control profile is easily set up by moving these points on the grid. SUN1, SUN2, and SUN3 are similarly controlled. These profiles, slightly staggered in time, are plotted together in the graph below.

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At the present state of LED technology, the lamps cannot be dimmed continuously through about the bottom 10% of capacity. This is why the end points of the traces do not go to zero.

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The above graph plots the pH monitors on each end of the tank. pH-R is currently the CO2 solenoid valve controller. The pH reported at any one time is the average of the two 7-day running averages rounded to the nearest tenth. The traces clearly show variability due to reaction-time latency and turn-on "overshoots", which I believe are normal transients, but the system running average is very stable.

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This is the 7-day ORP (redox in mV) trace. The average is what will be reported as the daily value. This redox is quite high for a system not using ozone. It is an oxidative environment and indicative of extremely low dissolved organic carbon (DOC). I refer to DOC hereafter as dissolved organic matter (DOM). There is a very large and robust bio-filter apparatus underlying this system, so aerobic heterotrophic and autotrophic processing are intensive. The final output, in addition to orthophosphate and nitrate, is DOM recalcitrant to further decomposition by aerobic mediation. This processing is supported by the ample O2 and CO2 available. With aquarium temperature held at 77 F (25 C) at the elevation here in Kansas City, USA, O2 saturation is 8 ppm. The plants achieve this by midday and the DO regularly increases to over 10 ppm. Under these circumstances, the prolific evolution of O2 tends to drive the ORP up over time.

A major factor supporting high ORP is the SWCR constantly removing a significant portion of DOM, as water changes are expected to do. The rate of dilution is regulated and broadly timed, so it is non-episodic in effect and promotes stability. The overall effect of the SWCR removing PO4, NO3, and DOM is the emulation of the flow, sending autochthonous product downstream, bringing in unloaded fresh water from upstream. It is an inexorable process of waste removal and is totally automatic.

The notch in the ORP trace begins at 07:00 and bottoms at 07:45. This corresponds to the time of day when all supplements that effect the redox are dosed. Flourish Comprehensive, Excel, and Advance cause this. These are the reduced/reducing organics - gluconate, protein hydrolysates (various amino acids and peptides), sugar alcohols, ascorbic acid, polycyclogluteracetyl - that depress ORP and DO, appearing immediately as a transitory spike in the COD (chemical oxygen demand). No other fertilizer, or any inorganic compound solution, has such impact on the ORP or the DO as this. ORP over the course of the day recovers to its normal high, showing at its peak the background DOM of environmental metabolism - or rather, the lack of it.
 
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Paul G

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Today's numbers

pH: 6.7
ORP: 495 mV
NO3: 1 ppm
PO4: 0.06 ppm
Fe: 0.07 ppm
K: 40 ppm
dGH: 3.1
Ca/Mg: 36/20 ppm
dKH: 7.2

The SWCR is balancing the K2CO3 dosing rate spot on. Potassium and alkalinity concentrations are steady at the desired values.

Macros PO4 and NO3 remain very low. A good deal of this nutrient is going to the plants, as the growth and health are fantastic, but the SWCR is certainly cutting into it as well. Iron is okay, and as I trust SeaChem's formulations, all other micros are fine too. That being said, I am bumping these just a little, and will continue with the copious feeding.

Of course, what has been discussed so far are water tests. These are all parameters in the water column. The plants do get nutrient from the substrate. I use inert washed river gravel, mostly composed of quartz with other insoluble clastics from the source rocks, 1 mm to 4 mm rounded grain, "very coarse sand" to "granular pebble" on the Wentworth scale. Pretty much what is sold as aquarium gravel. This is heavily amended by the addition of SeaChem Flourish fracted porous clay to provide some cation exchange capacity (CEC). This substrate is chemically stable and biologically inert. It can be relied upon not to exhaust or deteriorate or otherwise expire - forever. This was a deliberate choice; it removes all concern about the future of what the roots of my plants face. I do not need another variable to deal with.

However, I use substrate fertilizer tablets. Foliar uptake is not the whole picture. API Root Tabs are formulated for macro rich, and SeaChem Flourish Tabs tend more to the micros. I use both. I put in a couple of each around each swordplant about every 6 to 8 months. All the root feeders eventually get some of it. When I first plant, or transplant, I inject a suspension of CaribSea Flora-Spore arbuscular mycorrhyzal symbionts. In an aquarium as mature as this, these are almost certainly established throughout the substrate, but I do it for the karma; you do it only once, it does no harm, and it's inexpensive.

The GH test kit I use is the LaMotte 4824. It tests freshwater GH and Ca. I have used other reagent type kits and I think the LaMotte is probably the easiest one for obtaining relatively accurate results. It is a pro-grade field and facility kit and definitely not cheap. This test uses a color-change titration method. There is some opportunity for error in the practice of good lab procedure (particularly going too fast), and some subjectivity in the evaluation of the color. The burette calibrations are in 4 ppm increments, so it is quite easy to get a + or - 4 ppm error on any given test if your lab procedure is less than perfect. This, nevertheless, is superior resolution to hobby grade kits. I've been using this kit for years, so I'm pretty good at it, but I am not surprised that I sometimes get a GH or Ca number that is off a little more than I expected from the previous day's number. Nor does it trouble me, since it's already a fairly small margin in terms of the usefulness of the information, and I take more seriously the long term running average of the values. The largest data universe gives the most accurate picture. I have made a point of this because someone is bound to notice that these numbers look like they are bouncing around without a satisfactory reason for why the test should be believed.

More on the SWCR: this method is based on a timer program. The drain valve solenoid is controlled by a timer that establishes when the ODE (open drain event) will occur, and also how long the valve remains open. It is necessary that the ODE lasts long enough so that the waterline drop will trigger the ATO (auto top-off). Then, the timing is such that the drain will close when a discrete packet of tank water has been removed. This has all been determined by experimentation and will vary from system to system; there is no prescription. In the case of this tank, a 90 second ODE removes almost exactly 3.375 liters.

To allow dwell time for supplements after dosing, the ODEs are divided into two series, rather than trying to spread them out further. This permits a 6 hour post-dose period before the next water change (see 24 hour clock above). It happened after much tinkering, that the 7-and-7 90 second ODE scheme was effective and convenient, so that's where I landed.
 

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Just for the record, more plumbing and wiring. These block diagrams give the essential features of the system functions. Valves and unions are not shown.
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Today's numbers

pH: 6.7
ORP: 497 mV
NO3: 1 ppm
PO4: 0.06 ppm
Fe: 0.15 ppm
K: 40 ppm
dGH: 2.9
Ca/Mg: 40/12 ppm
dKH: 6.5

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Echinodorus sp

This is one of four large swordplants that have all been in this tank for at least six years. I do not know for certain what species (or cultivar) this is. I can't recall what it was sold as, but they were obtained from one source at the same time, so am sure they're the same. I would say they answer to ozelot, osiris, or "oriental". Leaves usually start decidedly red, sometimes holding onto red somewhat as they grow, many at some point get the small brown spots, and when very large go entirely green. These have extensive root systems and constantly put out numerous flower runners. Today I pruned and removed at least a dozen large leaves. I need to go back in for some major maintenance and a hardscape redo soon, so I will be trimming the crowns of the many stumps left behind.

On the left is Anubias barteri. This plant is dwarfed and mostly hidden by the sword. It needs to be moved, as do many of the Java ferns. A good deal of Sagittaria subulata was pulled up today, and a good deal was left in as well. As usual, the Hygrophila difformis was severely topped.

Today's numbers

pH: 6.7
ORP: 501 mV
NO3: 1 ppm
PO4: 0.05 ppm
Fe: 0.08 ppm
K: 40 ppm
dGH: 2.9
Ca/Mg: 38/14 ppm
dKH: 6.7