Hi. I'm new to fertilizers, and I'm having some trouble figuring out how much I should add to my 6 gallon tank (heavily decorated, so it probably holds 4-5 gallons of water). I've tried using the online fertilizer calculators, but they confuse me greatly.

If someone tell me what (approximate) amount of each fertilizer I should add, I would be very grateful. I ordered KNO3, K2SO4, Plantex CSM+B and KH2PO4 from aquariumfertilizer.com, and I also have a bottle of excel.

Thanks in advance

Take the EI example for 20 gallons and divide by 4.
That's what you'd need to add 3x a week.

Pretty small amounts huh?

Too small to do it decently.

So try this trick, add 4 week's worth into a 250 mls of water.

So 4 weeks x 3 doses = 12

Use 12/4 = 3 doses for a 20 Gallon.

So add 3/4 teaspoon of KNO3, about a little shy of 1/4 teaspoon for KH2PO4.
Add 1/2 teaspoon MgSO4, epsom salt.
Add traces, at 1.25 mls 3x aweek.

So 250 mls divided by 12 doses= 20mls each dose of the KNO3, KH2PO4 and MgSO4 solution. Add 1.25 mls of the trace.

That's it.
You can switch out GH booster for the MgSO4, but if your GH is 3 or higher, I'd not worry about it.

Regards,
Tom Barr

Tom, Thank you so much. I really appreciate you taking the time to help me.

So let me see if I have this straight...
I take 250 ml of water, and add 3/4 teaspoon of KNO3, slightly less than 1/4 teaspoon of KH2PO4, and 1/2 teaspoon MgSO4. Then, I dose 20mls of this solution 3x a week. Correct?

How do I add traces at 1.25 mls 3x a week? Do I make another solution? If so, how much should Plantex CSM+B should I add to 250 ml of water, and how much of that solution should I add to my tank?

Also, what about K2SO4? Do I need to add any of that?

Again, thanks for the assistance.

You got it.

Probably do not need K2SO4.

For traces: add 1 table spoon of the Plantex to 500mls of water.

Keep separate from the KNO3/KH2PO4.

And then dose the 1.25 mls.

So you dose 2 solutions.


Now you can dose daily if you wish and divide by 7, instead of dosing 3x a week.
So dose 8.5 mls of the Macro nutrients.
And 1/2 mls of the trace.

Really up to you.
You should get similar growth rates either way.
But depends on what routine will allow you to keep up on a good stable dosing routine.

As many feed their fish daily, this is not a bad time to also feed the plants.
Other than this, 50% weekly water change, cleaning, CO2 is mainly what is left.

These last issues are more important than dosing ferts though.
And generally neglected and cause more issues for folks.

So address that before looking at ferts.

Regards,
Tom Barr

Tom, thank you again for your assistance. Water changes won’t be a problem- I’m probably the only person who actually likes doing them. And I’ve been experimenting with a few different DIY CO2 bottles (trying to figure out the best recipe), so I should have that in check before the ferts arrive in the mail.