According to the calculator, if I add 1 tablespoon of KNO3 to a 90 gal tank, I would be dosing 20 ppm of Potassium w/c is the right amount ,but I'd be putting in 30.2 ppm of Nitrate and the required amount for Nitrate is only 5 ppm. Is this alright or its better to dose KH2SO4 instead for Potassium?

That was one of the first dosing calculators made and the advice is a bit out dated.
I do not use dosing calculators personally.

We have a nutri calculator here that's a good standard to follow.

I think 10ppm per dose for NO3 is good.
I think I dosed 3/4 teaspoon for about 7 years on my 90 gal, (see my avatar) 3x a week.

No need for K2SO4 dosing.
If you use the GH booster, then it's about 1/2 K2SO4 anyway but you only add that once a week after the water change.

There's more than enough K in virtually every tank so unless you have low light/non CO2 methods and/or a very large fish load, there's no cause for any concern.

You'd have to get at least 75% of the N from fish waste before dosing with KNO3 would not add enough K+.

KNO3 adds about 4.1 to 4.4 x as much K+ relative to N as a plant needs.
So roughly 75% or more of the N needs to come from fish waste before you might run into a deficiency of K+.

Note: adding a 3/4 teaspoon of K2SO4 after the water change will not hurt anything, but it will not help either.

High K+ has not been shown to cause issues in and of it's self, nor has NO3 in the 5-60ppm range near as anyone can tell or show from KNO3 dosing.

I've gone to 160ppm of NO3 using KNO3 without issue with the fish, I lost about 50% of the Amano shrimp after 3 days, but never lost one fish and all the fish later where fine from that short term exposure.

Long term chronic exposures at sublethal levels are extremely difficult to measure and do, aquarist are not equipped to measure that.

But many have used EI at full rates for many years and without issues.
So problems have not been apparent over several years both in my tanks and many others.

Regards,
Tom Barr

Tom, when you refer to the nutri-calc we have what do you mean? do you mean the guidlines in the EI threads or is there a full calculator Im missing?

Nutri-Calculator

Regards,
Tom Barr

ooooooooo thx Tom

Nutri-calc is brilliant, converts to grams for me too which is what I wanted.

It does however mention that I should be dosing MgS04 as well as K2S04, and alot of it as well, is this correct Tom?

It depends, I seldom use MgSO4 and K2SO4 individually, but...........

I use the GH booster which has a lot of both, so yes.
But it's not always required if you have harder tap water with Mg.

TMG also has a little K+ and Mg as well as traces.


Regards,
Tom Barr

Ill give it a try for a bit as its cheap and see how it goes.. wont hurt to try it

The GH booster rules out everything that the KNO3/KH2PO4/Traces do not.

The Barr's Matrix will have some K+/Mg in it as well and be a mixture of trace metal gluconate weak chelators and stronger DTPA metal chelators as well as a host of amino acids, hormones and very tiny amounts of non essential trace metals.

Takes the ratio of metals and traces and makes a different ratio specific to aquatic plants and practical use, as well as the best chelators for the various tap water KH's.

It'll work well when dosed daily as well as 1-2x a week folks.
I will be selling it in June 2007.

Regards,
Tom Barr