Dosing freshwater N-P-K macro additives to support macroalgae?

[sikorskys]

Hello there.

Since my pH drops to 7.5-7.6 at night, I'd like to run my fuge (c. racemosa) for 12h a day. The problem is, my tank is starving at zero nitrates and undetectable phosphates already, though I run fuge just for 6 hours a day.

It looks like dosing NO3 and PO4 will allow me to increase fuge photoperiod and thus making my pH a bit higher. Unfortunately, I can't find any saltwater nitrate & phosphate additives in my country. On the other hand, there are plenty of freshwater additives like Aquaforest AF Macro, created specifically to support plants.

So... Is it okay to use them in saltwater? Caulerpa is... a plant to some degree, right?

As for me, AF Macro looks totally fine, since it's effect on K, Mg and Ca is so small:

1 ml in 10 l of aquarium water will raise levels:

N Nitrogen 7,0 mg/l (ppm)
P Phosphorus 0,3 mg/l (ppm)
K Potassium 7,00 mg/l (ppm)
Mg Magnesium 0,9 mg/l (ppm)
Ca Calcium 0,2 mg/l (ppm)

 

[Peng1606]

Yes that will be ok to use. I switched to powdered nitrate and phosphate supplements from greenleaf aquariums rather than using the various liquid products... cheap and goes a long way... the amount I had to use in 750 gallons of water made it ridiculous how much of the premixed stuff I had to add. Also repeated ICP water testing has not shown any heavy metals etc showing up as contaminants after using the powdered stuff.

 

[Randy Holmes-Farley Verified Community Expert]

Hello there.

Since my pH drops to 7.5-7.6 at night, I'd like to run my fuge (c. racemosa) for 12h a day. The problem is, my tank is starving at zero nitrates and undetectable phosphates already, though I run fuge just for 6 hours a day.

It looks like dosing NO3 and PO4 will allow me to increase fuge photoperiod and thus making my pH a bit higher. Unfortunately, I can't find any saltwater nitrate & phosphate additives in my country. On the other hand, there are plenty of freshwater additives like Aquaforest AF Macro, created specifically to support plants.

So... Is it okay to use them in saltwater? Caulerpa is... a plant to some degree, right?

As for me, AF Macro looks totally fine, since it's effect on K, Mg and Ca is so small:

That is probably OK, but you may end up boosting potassium too much.

 

[sikorskys]

Yes that will be ok to use. I switched to powdered nitrate and phosphate supplements from greenleaf aquariums rather than using the various liquid products... cheap and goes a long way... the amount I had to use in 750 gallons of water made it ridiculous how much of the premixed stuff I had to add. Also repeated ICP water testing has not shown any heavy metals etc showing up as contaminants after using the powdered stuff.

Thank you! Separate nitrate and phosphate additives is what I consider the best possible solution too.

 

[sikorskys]

That is probably OK, but you may end up boosting potassium too much.

So I have to monitor my K and change water as needed.

Thank you Randy so much!