[NotThePainter]

We noticed this weekend that all of our tanks have very high nitrates, 40-80ppm. So of course we tested the tap, 20ppm. We live in a small town and on Feb 19th they switched wells. Clearly the current well has a problem. (And yes, we'll be calling the town today.)

I use EI dosing so I can guess one of two things has happened. Today is Monday and I do a 50% change on Saturdays.

1. The water out of the tap was much higher than 20ppm
2. My EI dosing has boosted the nitrates.

I'm certain that my EI dosing is not at fault because we have multiple tanks in the house, kept by my wife and I and only one tank has the EI dosing. The other high nitrate tanks have a much less vigorous dosing. (1/3 EI with 25% weekly changes and ad-hoc thrive with weekly 20% changes.)

So the question is now, what to do? My best guess is to:

1. Daily 50% changes until the ppm reaches tap
2. Stop the macro dosing

But if I stop the macro dosing won't I be deficient in P and K? I guess this is the disadvantage of all in one fert mixes.

The good news is that the fish don't seem to be suffering and we also expect this to be a short term condition.

Oh, and of course Ammonia and Nitrites are zero, these are all mature, planted tanks.

Thanks!

 

[Savetheplants]

I think two 50% water changes would get you off to a good start. Great news. You don't have to dose Nitrate anymore. Just dose P and K individually. You can make a solution for the P. You can dose K with measuring spoons.

KH2PO4 5,600 mg/tsp
PO4 69.83%

K2SO4 6,400 mg/tsp
K2 44.86%

If you don't already know. Divide the liters after displacement in your tank by the percentages above. For example, if you have 100 liters, divide 100 liters/69.83% PO4 = 143.20 mg KH2PO4 to dose 100 liters 1 mg/l PO4. Then multiply 143.20 by 50 to get the amount (7.16 grams KH2PO4) you will need to make a solution of 250 ml to dose your 100 liters. This will make fifty 5 ml doses. Each 5 ml dose will increase Phosphate 1 mg/l in 100 liters.

For K you divide 100 liters/44.86% K = 222.92 mg K2SO4 to dose 100 liters 1 mg/l K. Divide 6,400 mg/tsp by 222.92 mg K2SO4 to get an idea of how much K2SO4 to measure with measuring spoons. The answer is 1/25th. Well that's not very helpful so goto Rotala Butterfly | Planted Aquarium Nutrient Dosing Calculator and check there to get the measures. Rotalabutterfly says 1/32th tsp, which means 6,400 mg/tsp K2SO4 is wrong. That's the way this hobby goes. You go with what you know until you know better.

 

[NotThePainter]

I think two 50% water changes would get you off to a good start. Great news. You don't have to dose Nitrate anymore.

It is a false positive on the test kit, see API Nitrate - false positive. So I've resumed EI dosing as usual.

Just dose P and K individually. You can make a solution ....


If you don't already know. Divide the liters after displacement ....

That is really good to know, thanks!

 

[Savetheplants]

I learned something from this thread. I learned there are approxiamately 7,136 mg K2SO4 in one teaspoon. 32 x 223 mg. Glad to hear your water is good.

 

[NotThePainter]

It might not be a false positive, see the other thread. But if it isn't, then a big water change is called for. I'll monitor the fish and take a nitrate reading before and after this Saturday's 50% change.