Phosphate control in 20 gallon cube

nibes · Oct 7, 2023

sooo I have a water box cube 20, and am looking for some guidance. I have a bit of an issue with elevated phosphates. My recent results show a phosphorous of .41 ppm (.12ppm phosphate converted) and nitrates at 0. Currently have a small skimmer that I have now turned off for 12 hours to hopefully increase the nitrates a bit, I purchased phos fx, but I’m lost as to how much to introduce to reduce the phosphates. Outside of doing weekly water changes, is there anything I should be doing that I’m currently not doing? Should I use the phos fx? And how much should I use from the bag (250 ml bag size)? Thanks in advance for your assistance. For reference I’m currently using phytoplankton daily, reefroids sparingly weekly, and stopped pellets for my clowns and gone with only mysis for fish feed.

EeyoreIsMySpiritAnimal · Oct 7, 2023

How old is your tank? 0.12 phosphates is NOT high. I wouldn't do anything to lower them, just work on raising your nitrates. I believe reef roids is high in phos, so if anything, decrease that and increase regular fish food.

Also, what kind of phyto are you using? Live phyto will consume nutrients but dead phyto will add N and P to the system.

Randy Holmes-Farley · Oct 7, 2023

EeyoreIsMySpiritAnimal said:
How old is your tank? 0.12 phosphates is NOT high. I wouldn't do anything to lower them, just work on raising your nitrates. I believe reef roids is high in phos, so if anything, decrease that and increase regular fish food.

Also, what kind of phyto are you using? Live phyto will consume nutrients but dead phyto will add N and P to the system.

He means 1.2 ppm, I presume, based on the P value.

EeyoreIsMySpiritAnimal · Oct 7, 2023

Randy Holmes-Farley said:
He means 1.2 ppm, I presume, based on the P value.

That does make a difference

nibes · Oct 7, 2023

I must be misinformed, I thought phosphates were “ideal” between 0.01 and 0.03 ppm, and I’m using oceanmagik from algae barn. Is there something better to use?

Randy Holmes-Farley · Oct 7, 2023

IMO, it is more important to get nitrate up than the reduce phosphate quickly.

I’d dose sodium or calcium nitrate, ammonia, or amino acids to get nitrate up.

EeyoreIsMySpiritAnimal · Oct 7, 2023

nibes said:
I must be misinformed, I thought phosphates were “ideal” between 0.01 and 0.03 ppm

This range is only (possibly) "ideal" for super sensitive SPS that need an ULNS. 0.01-0.03 will likely starve the majority of corals.

nibes · Oct 8, 2023

Thanks for the feedback!!

jda · Oct 8, 2023

Water changes are not going to help to reduce phosphate much. They can help other things, so I would keep doing them.

You are going to need media if your po4 is over 1. Water changes and biological things (like growing bacteria or algae) are better at maintaining than lowering. This could take a lot of media - like a gallon of GFO changed every day with a few tablespoons in a reactor.

The po4 binds to rock and sand and will release when the water column po4 gets lower. You want to slowly lower your water column level so that the rock/sand unbind at a similar rate. Avoid driving the water column down really low and then having it bounce back up. The up/down EKG type of deal can be harmful.