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Discussion Starter · #1 ·
Hi,

I have very low phosphates level in planted tank (like always with API test hard to see the difference between 0 and 0,25ppm).
What is the desirable level? Do I need to rise it for my plants?

I also have green spot algae invasion due to low phosphates.

Thanks
 

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But how to dose theme? What element I need to dose? I cannot find phosphates ferts nowhere...
If I'll add more phosphates it won't cause others algae issue?
Adding phosphates and other fertilizers will not cause algae. There is a list of common fertilizers to use in the article I posted. I would recommend Nilocg here on the forum for purchasing your fertilizers. Here is a link to one of his for sale posts. Not only does he offer great prices, he also offers good advise and support. It's a win win if you ask me.
 

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Discussion Starter · #8 ·
I'm dosing Flourish comprehensive, API Leaf Zone and liquid carbon 2.5-3ml for 29g, low lights 28PAR LED.

How to mix and dose dry phosphates?
If the phosphates don't cause algae, why every body tried to lowering it?

So, I'm only need a Mono Potassium Phosphate (KH2PO4)- $5/lb $3 per 1/2lb?

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With a low light tank you may not need to dose Phosphate. One ppm is sufficient for plant growth. The other macro nutrient you should know is Nitrate. If it is over 5ppm this also would be enough for basic growth. Flourish comp can provide enough iron and trace elements. The API leaf zone will be sufficient for potassium and iron as well. So basically if you have enough nitrates you have what you need already. It's hard to say without all the parameters. NO3, PO4 and GH. If you have a GH over 4 plants should have enough Ca and Mg. All that said for $25 it's nice to have ferts on hand should you need to add more. The aim is to keep the nutrient levels in the ranges listed in that article whether high light or high tech. Low tech simply does not use them as fast so a lower dosing frequency will suffice. The only problem I see is if you do water changes. The nutrient levels will most likely fall shy of the minimum hence having some ferts just in case.
 

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Discussion Starter · #10 ·
One ppm will help me to destroy GSA? Right now my phosphates are 0-0,25ppm.
My low light is almost medium light (28PAR, medium is 30PAR).

My GH is over 4 for sure.
Nitrates test hard to read, maybe 30-40.
 

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One ppm will help me to destroy GSA? Right now my phosphates are 0-0,25ppm.
My low light is almost medium light (28PAR, medium is 30PAR).

My GH is over 4 for sure.
Nitrates test hard to read, maybe 30-40.
I also dose 1 ,1.5 ppm in my low light tank.Measured after third week of dosing ,with 50% weekly water change -

PO4 was around 1.8 ,right after WC and dosing.........and at the end of that week(right before the next WC) ,PO4 had dropped to about 0.3 -0.4.
I used the JBL PO4 drop test kit.Not sure it's accurate ,but at least gives me a hint about the uptake.
The weird thing is that GSA had also spread more.
 

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I find adding dry ferts directly to the tank is sooooo much easier then mixing it with water. If your nervous about doing it, do about half of the recommended dose wait a little then test, then add more in if needed. If you put to much in, no big deal your next water change will fix that. I'm lucky my tap has 2ppm phosphate. Whoever started the phosphate causes algae rumor needs the shame finger.
 

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Discussion Starter · #15 ·
To reach your target of 2.0ppm PO4, you'll need to add 402 mg of K2HPO4 to 29.0 gal.

How much is 402mg compare to tea spoon? How often I need to dose? Once a week? Twice or how?
 
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