Partial Nitrate Removal?

[bttay]

My tank has been having algae on the glass panel almost everyday for months. After some analysis (long story) I realized that the most possible cause is due to high nitrate as I have at least 20ppm of nitrate all the time most likely contributed by six discus and 50 other small fishes. (Btw, I have carefully dosed the correct amount of PO4, Fe, K and trace).

What I plan to do is to have small quantity of nitrate remover in my cannister filter to lower the nitrate level to about 10ppm. Does anyone here have such experience before?

[vinz]

Or go the other way and up the dosage for PO4 (first) and other ferts... but provided you have lots of light and CO2.

[victri]

How much PO4 are you adding per week? As Vinz suggested, increasing the PO4 can help as it encourages faster uptake of NO3.

[bttay]

Thank you for your helpful reply.

I have between 1 and 2ppm of PO4.

[bclee]

10 vs 20ppm of NO3 is not going to much of a difference. Try pushing CO2 up a little more.

Next you can work on PO4. Up by 25 to 50% dosage, observe the response.

BC

[juggler]

[quote:937984e42e="bttay"]Thank you for your helpful reply.

I have between 1 and 2ppm of PO4.[/quote:937984e42e]

I read somewhere in AQ that there are organic and inorganic versions of PO4. Plants can take the inorganic PO4. But our test kits measure both.

So, can try BC's recommendation to up PO4 dose slowly.

[bttay]

If adding more PO4 works, does that mean the plants are going to grow faster since the uptake of the other nutrients would be increased?

[Plantbrain]

How big is this tank?Do you over feed the Discus?
Back off feeding them so much till they are full grown. Consider raising them in a bare bottom tank till they are full size.
Doing 2x a week large water changes will help a great deal.

Adding K2SO4 in place of KNO3 may also help.
Or a ratio of 50:50 since you already have high NO3.
It's not the NO3 really, it's all the fish waste(urea and NH4) that is the issue here.

I add 20ppm or so of NO3 and I've not had any algae issues even at high light(5-6w/gal).
So if higher NO3 levels cause algae, I'd certainly see it.

The issue is more of doing water changes and the fish load/feeding routine I'd say. Back off live food and switch to frozen.

Regards,
Tom Barr

[bttay]

[quote:a8583ed388="Plantbrain"]How big is this tank?Do you over feed the Discus?
Back off feeding them so much till they are full grown. Consider raising them in a bare bottom tank till they are full size.
Doing 2x a week large water changes will help a great deal.

Adding K2SO4 in place of KNO3 may also help.
Or a ratio of 50:50 since you already have high NO3.
It's not the NO3 really, it's all the fish waste(urea and NH4) that is the issue here.

[/quote:a8583ed388]

Thanks Tom for your valuable advices. My tank is 4 x 1.5 x 2 ft. I don't overfeed the fish. I hand feed them with frozen bloodworm, brine shrimp and beefheart, I make sure that they finish within a min. Unfortunately, I can't follow your advice to raise them in another tank as I have limited space, resources and time.

I do not dose KNO3 but dose K2SO4 after each water change.

I will try increasing PO4 dosage and monitor the result.
(Juggler: The above is also in response to your message. Tks.)