EI dosing on water change day only

hbosman

Guru Class Expert
Oct 22, 2008
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Leesburg VA USA
Hello All,

I was wondering what the drawbacks would be on dosing NPK only on water change day. I dry dose EI currently but would like to dose only on water change day. I do 50 % water changes a minimum of once a week, often twice a week if I'm not to busy. I would still be dosing fe via csm+b and dtpa on a daily basis.

The tank is a 46 gallon bowfront so I was going to try the following after 50 % water change:

.75 teaspoon kno3
.125 (1/8) teaspoon KH2PO4
.125 (1/8) teaspoon K2SO4

I will continue to add 1/16 teaspoon fe per day.

the fe is from csm+b and dtpa at a ratio of 4:1.

Lighting is 4x39 watts 2 bulbs for 7 hours, all four bulbs for 1 hour.
pressurized co2 - yellow green drop checker (4kdh) fluid 10 hours.
korallia nano and Rena XP2 for water movement.

Appreciate thoughts on this.
 

Biollante

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Jun 21, 2009
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Give It A Try

Hi,

I am not sure there would be anything wrong with “pulsing” the macros. I think the idea has been to keep the nutrients level through the week keeping the nitrates for instance under 10-ppm. :rolleyes:

I run tanks much higher levels of nitrates and have found no harm. :cool:

I have been “pulsing” iron for a while and it “seems” beneficial, at any rate has done no harm that I can tell, sort term anyway.

Some of the stories I hear, I think a lot of people are actually doing that intentionally or not. :eek:

Try it and tell us what happens. :)

Biollante
 

hbosman

Guru Class Expert
Oct 22, 2008
277
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18
Leesburg VA USA
I want to try this for two reasons. One is, it would be less time consuming and the other is, I was wanting to see if nitrate consumption could be measurable via a cheap test kit. My guess is the AP test kit wouldn't indicate a change in nitrate levels because it isn't graduated enough and the nitrate level might be maintained from the addition of fish food and decaying organics.

I was wanting input before I try it and risk dying plants or an onslaught of Algae if it turns out to be a bad idea.
 
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Biollante

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Jun 21, 2009
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Alae Is The Risk

Hi,

I doubt a week or two’s worth will do any irrevocable harm. Who knows it may turn out to be a superior dosing method. :)

If you have reasonable growth, you should see a significant drop in nitrates. :gw

Remember to account for fish food. :)

Biollante
 

Gerryd

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Sep 23, 2007
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South Florida
Hi,

If you do more than 1 water change weekly, do you plan to dose after each one? If not, you will reduce nutes by the extra water change..............

I think it will 'work' but may not be optimal.

Tom had a point that we feed the fish daily, why not the plants? Makes sense to me.............

I would be concerned about insufficient amounts of nutrients at the end of the week. Esp with good c02 and a lot of light, you will be pushing them pretty hard.

I think your tank will be pretty lean by the end of the week. Do you have a lot of bio-mass? You do have a lot of light IMO........
 

hbosman

Guru Class Expert
Oct 22, 2008
277
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Leesburg VA USA
I would add ferts after the second water change as well. Currently, I do EI and add kno3 and my iron dry mix daily and add k2so4 and kh2po4 after the water change. I don't see a reduction in the phosphate at the end of the week and wanted to see if the nitrate level wouldn't change so much as well. bio made a point that nothing bad would happen in a week or two. I went on vacation for a week and no dosing occurred, not even fish food. The glass was unbelievably clean for some reason. Maybe had something to do with Rotala covering the entire water surface.
 

Gbark

Guru Class Expert
Jun 15, 2009
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I have always wondered why we dose daily and not weekly.

I know TPN suggest to dose once a week.

We don't feed our garden plants daily.
 

Gerryd

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Sep 23, 2007
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Gbark,

Yes, but garden soil is pretty rich in nutrients and c02 is unlimited along with plenty of great light :)

I usually dose 3x weekly, once a week just seems too long to me.........

Even with 'good' c02 and say ADA AS, you can't match to an outside garden.......
 

scottward

Guru Class Expert
Oct 26, 2007
958
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Brisbane, Australia
The dosing of macro nutrients is spread out over several days purely to prevent poisoning the fish...isn't it?

Once the macros are in the water, the only way they are removed is by the plants....correct? I understand that micro nutrients need to be dosed more frequently as, for example iron, can become unusable to the plants after a certain amount of time in the water? But macros are pretty stable I think?

Provided the total NPK levels aren't toxic to the fish, I can't see any reason why they couldn't just be dosed after a water change?

Personally, even if I could dose the macros once a week, I don't mind doing it 3x per week anyway, I feed the fish and the plants! ;-)

Scott.
 

hbosman

Guru Class Expert
Oct 22, 2008
277
1
18
Leesburg VA USA
figuring 40 gallons of water,

.75 teaspoon kno3
.125 (1/8) teaspoon KH2PO4
.125 (1/8) teaspoon K2SO4

would give me,

15.8 ppm N
3.23 ppm P
13.66 ppm K

My current daily dosing of N gives me alittle more N than is listed above but I don't register a reduction when measuring prior to a water change. But, I am basing this on an uncalibrated AP test kit. Testing untreated tap water doesn't indicate N at all while testing prior to a water change is bright red which could be 10 or 40 ppm. In either case, I wouldn't think the plants are not limited.

my current dosing is .25 teaspoon 5.27 ppm on water change day and .125 teaspoon 2.63 ppm daily after that. These numbers come from the Fertilator on APC and they are consistant with the results from other calculators I've tried.

It would be nice to find an easy way to guesstimate weekly consumption of N. I'm not stressing about overdosing N though. I have read enough here and elsewhere to be confident that anything under 80 ppm should be considered safe for the fish and shrimp. After all, there are folks who have rather high Nitrate levels in their tap water without issue. If, these folks are advised that they don't need to add Nitrate, I would think that if I add sufficient KNO3 on water change day, that would be a similar situation.

Let me know your opinions, even if you think this doesn't make any sense. :)
 
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Tom Barr

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Jan 23, 2005
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I suggest dosing every so often based on the rates and ranges maintained by that dosing rate.

So : a stable, or semi stable ppm = stable enzymatic uptake machinery in the plants.
Also, no feast or famine or algae due to the dosing getting too far away from us.

For most aquariums, 2-3 x a week is about the min range instead of weekly if you use CO2, if not?
No CO2: Weekly or even 2x a month is good.

Sediment: If you use soil, ADA As, then you will have more flexibility, till the N runs out about 1-2 years down the road.
Light : If you use less light, then uptake and thus stability will be easier.

Those are the big 3 factors that can help move towards this goal.
They have trade offs, but you might be okay with them and many match up since you want less work over time.

Less pruning, less dosing errors, reduced growth etc, more % uptake of waste from fish etc.
Slow things down with no CO2, low light, good fish loading/feeding, soil sediments etc........now there's no much labor involved and no water changes............

You should try the EI modeling calculator here to estimate the different scenarios for build up of various nutrients, it even has fish waste contributions you can add to the model.

Should give you all the outcome estimations you are interested in.

Regards,
Tom Barr
 

scottward

Guru Class Expert
Oct 26, 2007
958
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Brisbane, Australia
So : a stable, or semi stable ppm = stable enzymatic uptake machinery in the plants.

Ah ok, I understood that the plant machinery likes a stable level of CO2, but I didn't realise that they also liked reasonably stable levels of macros. Makes sense now.
 

hbosman

Guru Class Expert
Oct 22, 2008
277
1
18
Leesburg VA USA
The EI calculator was extremely helpful in helping me decide my new EI dosing regimen.

http://wet.biggiantnerds.com/ei/con_v_time.pl

Wet, thank you very much!


I have a 46 Bowfront (40 gallons H2O), pressurized CO2 mist with yellow green drop checker (4kdh), 2x39 watts T5HO for 7 hours and 4x39 for 1 hour.
Water movement is provided by Rena XP2 (inline co2 atomizer) and a Koralia Nano.

I used the calculator based on a 40 % water change.

I'm going to dose:

3.23 ppm kh2po4 1 once per week
5.27 ppm kno3 3 times per week
7.02 ppm potassium from k2so4 and kno3 3 times per week

.18 ppm micros (csm+b and dtpa 4:1) 7 times per week

The potassium is a little higher than necessary (I think) but makes measuring easier with a dash spoon.
 
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Tom Barr

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TheKillHaa;50083 said:
i thoug micros (Fe) and Phosphates cant be added at same moment..

where i lost?

It's fine, just not the concentrated stock solutions.............

I've done it this way all my life without issues.

Regards,
Tom Barr
 

jonny_ftm

Guru Class Expert
Mar 5, 2009
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I've also always simplified it by dosing micro and macro on same day, give you 4 days/week free to watch your tank. Plants just like it. I also now moved to a pulse in dosing on WC day, but didn't really notice an improvement, it just gives me peace of mind