Just confused about PO4 and RowaPhos.

Tyler Bullock · Oct 26, 2021

I have a 90 gallon tank, not a lot of corals, been trying to keep my P04 down for some time. Dreaming of a majority acro dominated tank. I test my p04 about twice a week. I run RowaPhos all the time. I usually do 7 tbsp of the stuff when I change it out every two weeks. It keeps it down around .03-.05. The 2nd week after my change It jumps up to about .08-.1 by the end of the week. I do a majority of my maintenance on sunday. I feed 1 cube of frozen mysis 5 of the 7 days a week. Then feed two small pinches of PE Flakes a day for the other two days. The fish I have is a Tomini Tang, 2 x anthias, and 2 clownfish. Handful of snails and two shrimp.

Is this normal having my P04 raise so quickly? Reading other posts and they say they don't change out Rowaphos for like 2-3 months. Should I use more RowaPhos? I'm kinda clueless on what to do here.

Dolphins18 · Oct 26, 2021

Tyler Bullock said:
I have a 90 gallon tank, not a lot of corals, been trying to keep my P04 down for some time. Dreaming of a majority acro dominated tank. I test my p04 about twice a week. I run RowaPhos all the time. I usually do 7 tbsp of the stuff when I change it out every two weeks. It keeps it down around .03-.05. The 2nd week after my change It jumps up to about .08-.1 by the end of the week. I do a majority of my maintenance on sunday. I feed 1 cube of frozen mysis 5 of the 7 days a week. Then feed two small pinches of PE Flakes a day for the other two days. The fish I have is a Tomini Tang, 2 x anthias, and 2 clownfish. Handful of snails and two shrimp.

Is this normal having my P04 raise so quickly? Reading other posts and they say they don't change out Rowaphos for like 2-3 months. Should I use more RowaPhos? I'm kinda clueless on what to do here.

Yes, its not uncommon.

Sometimes rock that was used previously, and even new rock in some cases will be stuffed full of po4 that slowly releases into the tank.
It takes time and a lot of GFO to get it down again. High capacity gfo can help, and the other thing that is helping is starting with about half your usual dose so 3-4 tbsp, and you'll likely notice that decreases it to the same extent as the 7. It will exhaust but just keep adding a tbsp a day (or whatever is needed) and testing until you have a good schedule adjusted. You need to keep testing because eventually your rock wont leech anymore and then you will need to lower your gfo to only take care of added feeding po4.

Randy Holmes-Farley · Oct 27, 2021

Each daily feeding of food likely adds about 0.02 to 0.3 ppm per day of phosphate into the system, so it can rise and fall rapidly if the input and sinks do not match up.

0.1 ppm phosphate is not a reason that one cannot have acropora corals.