Battling Hair Algae in High Tech Aquarium, Fish Stressing Before 30 PPM CO2 Reached

dsm555

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Oct 23, 2021
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Hello,

I have been running a 25 gallon planted aquarium with pressurized CO2, set up for 11 months and have been battling algae since about week 3. The tank originally had a massive diatom outbreak lasting 1 month+ followed by green fuzz and green hair algae on substrate rocks and plant leaves. I have experienced a multitude of problems which I have attempted to approach systematically but so far been unable to solve.
Plant growth has been consistently stunted/slow. I have had melting/algae covering anything moderately difficult to grow, and even the rotala has curling new leaves, and gathers hair algae on older leaves. I have attempted multiple iterations of monte carlo (6 pots covering front half of aquarium) and the first couple of attempts I got moderate growth before it was choked out by algae. The last two attempts it has melted completely with the exception of a handful of very small leaves hanging on.

20211023_172106_HDR.jpg


My main suspect is low CO2, I have a fluval drop checker and use the supplied solution, which to my understanding is already a 4dkh mixed indicator solution. CO2 begins 90 minutes before lights on. I am currently running around 2.5 bps through a diffuser placed in the down wash current from the lily pipe output. Visually it appears there are a lot of bubbles being initially forced downwards throughout the aquarium. I have had quite a bit of difficulty getting and maintaining a green drop checker. I will gradually increase the CO2 over the course of a few days but before I am able to get the drop checker a nice lime green, the fish begin to show signs of stress. The white clouds in particular will hover at the water surface and show lethargy. I initially had 10 before gradually losing 7 over the course of the tanks life and recently added celestial pearl danios. I also lost 4/5 amano shrimp coinciding with attempts to gradually increase CO2 levels. I suspected possible low O2 levels but have attempted running an additional submersible pump directed towards the surface, and now running an airstone during the night to no improvements. Fish still show signs of stress before I can achieve a green drop checker. The best coloration I can get in the drop checker is displayed below, kind of lime green on top and blue/green on bottom. I have to say my camera makes it look more yellowish than in reality. Regardless, the fish were stressed at this level, in the image a white cloud can be seen through the lily pipe in the top left corner, farthest from the CO2 diffuser. This image was taken at the end of the CO2 cycle.

20211023_172125_HDR.jpg

20211023_175302_HDR.jpg


I have tried placing the drop checker right above the CO2 diffuser to confirm it will actually turn green.

I am at a bit of a loss here and am not sure if the root cause could be:CO2 and how to increase it if fish are stressed, fertilizer/poor plant growth, or ideas I haven't considered. Obviously these things may be related.

Tank Specs: 25.3 gallon 60 x 40 x 40 cm.
Light: Finnex Planted+ 24/7 running on a timer at 100% intensity for a 6 hour photoperiod.
Fertilizer: Aquarium Co-op Easy Green dosed daily to equate to recommended levels for a high light tank.
Filter: Fluval 207 canister
Water Changes: 25% twice per week
Plants: Rotala Rotundifolia green, Rotala H'ra, Hydrocotyle tripartita japan (algae on older leaves), Hygrophila pinnatifida (algae covers leaves), Some cyrpts (alage on older leaves), Dwarf Hairgrass (new), alternanthera reineckii mini (melted), Monte Carlo(mostly melted), staurogyne repens (mostly melted).
Stocking: 3 white cloud mountain minnows, 10 celestial pearl danios, 1 otocinclus, 1 amano shrimp.
Temperature: 73 °F / 23 °C
Ammonia: 0
Nitrite: 0
Nitrate: ~20 ppm
GH: 7
KH: 0
pH: 6.5
Substrate of fluval stratum buffers to 6.5 pH and reduces KH
 

Paul G

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I am not that good at diagnosing other folks' aquariums and I am not comfortable giving advice, so here is a question instead:

You have 0 alkalinity, and you appear to be trying to minimize your KH deliberately. What is your rationale for this?
 

dsm555

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Oct 23, 2021
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Sorry I see how that is unclear. My goal was not to reduce KH by adding the fluval stratum, but rather seems to be a property of fluval stratum reducing the KH to <1 ad buffering to a PH of 6.5. This was chosen at setup and I was unaware it had this property.
Water from my tap is treated with dechlorinator and comes out pH 7.2 - 7.4, GH: 1 KH: 1-2. I add seachem equilibrium to achieve the GH of 7 in the tank. I am not sure if increasing the KH is easy to do when the substrate is actively working against me. The substrate is getting older though at 11 months.

Another note that may be related to my substrate. When I first set up the aquarium I got growth from the alternanthera reineckii mini. It put out new leaves and while it never got nice and red (more of a brown) the plant looked relatively healthy. About 3 months in the melt started and I blamed increasing algae levels on the leaves. Now I have attempted to replant twice in the last 6 months and it has immediately melted both times. Perhaps the substrate is out of nutrients? It has been roughed up a few times more than it likely should removing algae and dead plant matter.
 

Allwissend

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I would suggest reducing the light to 50 or 20% for 6h . The plants you have will be able to cope with lower light levels for a few weeks while you figure out the CO2 situation of the aquarium.
Also get yourself a new toothbrush and the algae scraper and clean the tank followed by a water change. Clean the rocks, diffuser , glass and plants when possible. You are a great algae control mechanisms.


CO2 wise
- fish will respond to a rapid increase in CO2 faster then your dropchecker. Fish will be able to adapt to tolerate higher conc. of CO2, though pretty much every fish should do ok in 30 mg/L CO2 without serious issues. With that in mind, watching fish behaviour is a pretty good way to see when you are near the target.
- i would suggest starting the CO2 even earlier rather than increasing the rate. This might make things easier to control. Start 4 hours earlier and see where you get by the time the lights turn on
- clean the drop checker with distilled water on the inside and dry it really well with a paper towel. Try to not contaminate either the dropchecker or the liquid you put into it with any mineral deposits or water from other sources. The liquid in there will not indicate correctly if the solution gets contaminated and moves away from 4 °dKH

The rotala seems to be on the way to recovery so in a few days you will be able to cut them and replant the healthy tops. There is hope :)
 
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Paul G

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There is more to getting carbon to the plants than merely bubbling CO2 through the water. If your KH is 0, there is no bicarbonate/carbonate equilibrium buffering system operating in your system. The CO2 dissolution will not work as desired without some concentration of alkaline buffering.

Very generally, biologically friendly water will have dKH more or less equivalent to dGH. This is because natural water that contains calcium/magnesium will typically also contain carbonate since the principle source of these ions is the dissolution of earth-alkali carbonaceous rocks. 'Normal' moderately hard water with circumneutral or slightly higher pH is naturally buffered. The softer the water the greater the need for buffer supplementation if you want to maximize the usefulness of CO2 injection. CO2 dissolution, KH, and pH are in a three-way relationship. Your water is moderately soft in terms of both GH and KH. Equilibrium is sulfate salts and, by design, provides no buffer. As you are reconstituting your GH with Equilibrium, I suggest you also reconstitute your KH with Alkaline Buffer.

I don't know by what specific means your substrate lowers pH. I suspect it contains an acid buffer, the idea being that slightly acidic rhizozones promote a redox condition favorable to nutrient uptake. This is the idea behind the practice of amending gravel with peat. I would not let that deter me from adjusting the dKH of my water column. It may take a while, but I think your problem will abate when you normalize your water composition.

I would be interested to know your PO4.
 

dsm555

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Oct 23, 2021
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I have tried reducing light for a ~1 month period in the past to little effect. I am willing to try again but would like to try a couple of other things first. I will give the tank a good cleaning and replant the tops of the rotala as they grow. I have been moving these to the foreground as a means of increasing plant mass while I attempt to balance things out.

I can definitely start CO2 earlier. I think I'll start at 2.5 hours before lights on and see how the drop checker looks/adjust start time from there. I also have additional drop checker solution so I agree this is worth changing.

I will also try to increase KH and see what happens. My research seems to indicate the substrate will pull it back down to 0. Do you recommend continuing over the course of a few weeks until I am able to measure some KH? Of course too early to say for now what will actually happen.

I picked up a test kit for PO4 and the results would indicate 0 or close to it.
 

dsm555

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I have increased KH during my water change in the tank to 4 degrees measured via test kit. Before the adjustment levels still measured <1. I will continue to monitor and see how things look.
 

Paul G

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Yes, I think you would want to try to get the KH up. dKH = 4 is a good place to be. It may drop again. Ultimately, whatever in the substrate is eating the buffer will be neutralized, if that's what's going on. You are bound to get to where the value dwells at something stable. When you do your 25% water change, there will be some experimenting with adding makeup buffer so you don't lose your level.

It is unusual, but not impossible of course, to have NO3 = 20 ppm and 0 PO4. Check it just before you do your next water change.
 
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Lmuhlen

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I've had people telling me that there needs to be some KH for the CO2 to dissolve more easily or something like that, but I never understood the reasoning for that. I understand that CO2, carbonic acid, bicarbonates and carbonates are all connected by means of their reaction equlibrium constants, somehow, and that would have a direct impact on how the CO2 concentration affects the pH of the water, but what is it about KH that makes CO2 easier to dissolve or more available to plants or more beneficial in some way other than a more stable pH? From my basic understanding of reaction equilibrium, I would imagine that having no KH would lead to excessive CO2 being pushed into forming more carbonates, which would somehow work as a reserve of dissolved carbon, maybe? But that sounds like a good thing, not a bad thing.
 
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dsm555

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You make a good point @Lmuhlen.

I guess my understanding is:
CO2 + H2O <=> H2CO3,
H2CO3 <=> H+ + HCO3-, or H2CO3 <=>2H+ + CO3--
I am not sure that the resulting carbonates are the preferred carbon source of the plants. Increasing KH is done by adding carbonates and bicarbonates and this does not increase the amount of CO2 in the water. So perhaps adding carbonates and bicarbonates reduces the rate of the above reactions leaving more dissolved CO2 in the water?
The basic equation for photosynthesis is CO2 + H2O -> C6H12O6 + O2, but of course I may just be missing intermediates.
This is just my theory and may be heavily flawed.
I found a few interesting points in this discussion.

That said I checked KH today and after 24h it has dropped from 4 to 2. This is not as bad as I suspected from some other forum posts. I will continue to try and stabilize it and provide updates. Hopefully the 11 month old substrate is nearing the end of its buffering capacity.
 

Lmuhlen

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Please elaborate. My understanding is that all the table says is that the pH will drop more if I add CO2 to a low KH water, not that it is harder or less effective to add CO2 in a low KH water.
 

Paul G

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What it means is that you can maintain a stable desirable pH and increase the CO2 to the extent that the KH will permit.

The alkalinity is a buffer, allowing the solution to resist pH changes when the acidifying agent is increased. Thus, the living things in the system, fish, plants, bacteria, are kept at a pH that is acceptable to them, but you are able to increase the concentration of dissolved CO2. This is favorable to all autotrophic organisms, but you won't gas your fish to death in the bargain.
 

Paul G

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I think I could more clear about this.

As you inject CO2, you create carbonic acid, and this lowers the pH. If the water has no buffering - that is 0 alkalinity - the pH will drop rapidly and far, depending, of course, on how fast (how much) CO2 is going in. Buffer that sets up a carbonate equilibrium system would tend to prevent the pH from changing. In the absence of CO2 injection, the buffer will tend to stabilize the pH, and possibly even raise it slightly. With higher alkalinity, it is now possible to inject CO2 without drastically depressing the pH. If the CO2 injection rate is sufficient, the pH may be depressed somewhat as carbonic acid increases, but it will be stable, controlled. The buffer prevents the bottom dropping out.

The chart is the relationship between CO2 solution, KH, and pH. This is the carbonate buffer system. Of course, it depicts the pure relationship; there is no accounting for confounding variables, etc. but that's beside the point.

KH is very easily measured and adjusted. It is the one variable in the relation over which you have complete control.


The drop-checker method requires skill. Having no buffer at all is a needlessly self-inflicted handicap. And it's dangerous to fish.
 

Lmuhlen

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In this case, I don't think the improvement of the KH will help dsm555 with his current problem, even though it is still a good thing to improve.

My opinion on his issue is that if he wants more CO2 dissolved without having his fish gasp for air, he needs to improve the oxigenation of the water, with more turbulence at the surface. This would increase the degassing of CO2, so even more CO2 would be needed.

But before going this route, it is important to be sure that the fish are stressed at a relatively low level of dissolved CO2, so double-check the current state of the drop checker as Allwissend suggested. Although if there is contamination of the solution, in your case it would certainly reduce its KH and that would make the color move to yellow more easily... You could also test the pH drop of the water from a degassed sample to a sample with CO2 injected.

I don't know your substrate, but maybe the plants are somewhat phosphate starved? It could be worth it to dose some phosphate to detectable levels, paired with good maintenance and phisical removing of algae. Your issue is, before anything, plants missing something. Even if your CO2 isn't at optimum levels, it seems to be high nevertheless.
 
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Paul G

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Get your KH to 4. If aeration is inadequate, address that. If PO4 is deficient, address that. But get your KH to 4.

Paul G out.
 

dsm555

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Thanks for the advice. Still working on KH, I see no reason not to shoot for the 4 dKH suggested. As of yesterday it was still at 2, still supporting that my substrate is not immediately buffering it out. My next water change is tomorrow and I will bring it back up to 4.

CO2 progress has been good. I am running slightly higher CO2 than I have been able to in the past and the fauna do not appear to be showing signs of stress. Drop checker color is still not quite where I want it. A big thing that may be helping is running an airstone during the night which has removed a thin surface scum I regulaly would see build up. I had been removing this manually but it was rather stubborn and even running the lily pipe outflow such that it interupted the surface only removed it in the ~20% area immediately in front of the outflow. Running the airstone at night has removed it completely.

In summary the adjustments I have made so far:

KH increased from 0-2 (target 4)
Airstone running at night (started about 2 weeks ago)
CO2 started earlier, 2.5 hours before lights on. Very slowly increasing bubble rate. Shooting for about 1 adjustment per week.
 

dsm555

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Before my water change yesterday I re-measured the phosphate level in the tank. This time I measured right about 1 maybe 1.5 ppm of phosphate. The scale jumps from 1-2.5 and based on my judgement it is closer in color to 1. I also discovered the error made during my false 0 measurement from the other day. The instructions say to add a drop from the last dropper and then shake well but on the bottle it says to shake "very well" before use. This altered the consistency of the last solution and certainly impacted the 0 result I measured the first time around.
Levels of phosphate > 1 ppm can begin to cause issues right? I am not sure what is normal in a high tech set up.

I already own Seachem Phosguard which I ran in my filter for about a month long duration a good ways back. I had found indications that all the fuzzy green algae I had may be linked to high phosphate but never took the time to pick up a kit and measure. It is not in use currently. I am adding some phosphate with my all in one fertilizer Easy Green. It contains 0.46% phosphate. At 2.1 mL dose per week = 0.0096 mL phosphate. Assuming 20 gallons of water in a 25 gallon tank I am getting ~0.13 ppm pf phosphate dosed per week. the rest I would guess is coming from source water or plant decay from my long history of melting plants.

Ill update with results from tap water supply.
 

dsm555

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Unfortunately I am still having issues balancing things out. I measured phosphates before my water change again to day and it was back down at or very close to 0. I re-measured to be sure and got the same result. I still have new green hair/fuzz algae growing on the plant leaves, rocks, and substrate. I scrubbed away with a tooth brush again today during my WC. There isa new brown fuzz stuck in/on some of the plants, I was hoping this was dead algae but its hard to tell, I have added an image.
20211101_190016_HDR.jpg

It comes off the leaves no problem and seems to be more stuck in them, than growing on them. But if any algae is dying in my aquarium it is quickly being replaced by new.
The rotala rotundifolia green is still showing the same issue as previously with curling new leaves. Not all but some of the largest plants are impacted.

20211101_190212_HDR.jpg


Here is an updated before the cleaning today
20211101_190047_HDR.jpg


At this point I am planning to continue dosing fertz and CO2 at the same rate but reduce light intensity to 50% in an attempt to slow the growth of the hair algae.

As an additional question, should color of nitrate test be read with a solid backlight? I find it is difficult to interpret the color of the test and I often could be at either 10 or 20 PPM nitrate from what seems to be a subjective measurement. Not sure if anyone has opinions or tips on how to best interpret the color.
 
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Paul G

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It's going to take some time. The aquarium is an ecosystem; biological cycles can have some inertia. When you first alter a chemical parameter, the changes that occur in the types and amounts of bacteria, fungi, and algae adjust spontaneously, but not instantly. The changes in the aquarium that are not so drastic or abrupt as to cause outright harm may not manifest as immediately detectable results. Once an algal type establishes a viable population it can be tenacious. As aquariums that remain generally healthy mature over time, the algal community changes.

PO4 and NO3 are not strongly limiting to algae, as most kinds can get by on the most vanishingly small amounts of these nutrients. It is rightly said that they do not cause algae. But it is clear that when PO4 and NO3 is in plentiful supply, algae populations already present increase. Dissolved organic matter, as much a product of total environmental metabolism as NO3 and PO4, also plays a role. Algae are aquatic organisms and they will persist naturally in the aquarium. The question of interest relates to nuisance algae, which is about suppression of the population, not whether it can be exterminated completely. My experience is that the susceptibility of an aquarium to nuisance algae is a result of the overall trophic status that prevails over time. The way out of a nuisance alga situation is the perpetuation of trophic status that is favorable to higher plants and less favorable to algae. Time and patience play a role.

We have come to accept NO3 as non-toxic in the aquarium to the point that we see no problem whatever in levels as high as 20 ppm. What is the real difference between 20 ppm and 10 ppm? The algae don't care. What about 5 ppm? How low can we go before this important macro-nutrient becomes limiting to plants? Will this concentration then be limiting to algae? It will not. How much dissolved organic matter is in there? If your NO3 is 10 or 20 ppm, probably there is quite a lot of DOM, especially if you are not using sufficient chemical filter media to remove it. Likewise, if your NO3 is 10 or 20 ppm, 1 ppm of PO4 would not be surprising.

Focusing on the difference in test results between 10 and 20 ppm NO3 is not giving you information you can use. Holding NO3 below 5 ppm consistently and perpetually will start to matter, if the PO4 can be similarly held under 1 ppm, and if the DOM is well managed, and if the oxygenation is optimal, and if potassium is not deficient, and if the pH is kept stable, especially using CO2 injection. Maintaining these conditions yield a baseline trophic status that is more advantageous to macrophytes than to algae.

These embody general principles only. In terms of "do this - don't do that" advice I have only been insistent about stabilizing the pH by having a sensible KH. Keeping GH and KH at realistic values that are biologically friendly is an absolute must do. Stability of the pH is paramount.

A further suggestion along this line is, along with keeping lights reduced for now, lay on an aggressive chemical filtration regime for a couple of weeks at least. I don't know what kind you normally use, or how much, but I expect it could help to amp up with a high quality GAC and/or Purigen load. Purigen works especially with proteinaceous waste and may help with the NO3 evolution. I expect the resulting reduction of DOM to have a desirable effect. It will take some time.
 
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