Struggling to keep phosphorus levels UP in 2.5g pico


Active member
2.5g Pico Reef (Fluval Spec III), roughly 5-6 months old.

Using a Kessil A80, preset heater and Sicce Micra with RFG nozzle as a return/flow pump combo.

- Scarlet Cleaner Shrimp
- Red Hermit Crab
- Emerald Crab
- 2x Frogspawns
- 2x Acans
- 2x Ricordias
- Gorgonian
- Alveopora
- Chalice
- Blasto
- Montipora

Filtration consists of filter floss and a half box of MarinePure Gems in the overflow. That's it. No carbon, GFO, skimmer, macroalgae, carbon dosing or anything.

I dose 1.8ml of Tropic Marin All-For-Reef using a single Kamoer X1 Pro to maintain Ca/Alk/Mag at a steady 420/8.0/1300. I top off daily with RO/DI water to maintain salinity at 35ppt.

Acans started looking shriveling up and losing color. According to my Hanna phosphorus checker, I was at 0ppb. The other corals are still normal.

I fed an uncomfortably large amount of Reef Chili and frozen Mysis daily for almost two weeks straight without replacing the floss or doing any water changes. Acan condition slightly improved, the other corals looked ecstatic, the pod and Spirorbid populations exploded.... but phosphates and nitrates refused to budge from flat zero.

Started dosing NeoPhos and NeoNitro to help:
- Day 1: Nitrates at 0ppm, phosphorus at 0ppb. Dosed nitrates up to 3ppm and phosphorus to 6ppb (0.018ppm)
- Day 2: Nitrates at 2ppm, phosphorus at 0ppb. Dosed nitrates up to 5ppm and phosphorus to 33ppb (0.101ppm)
- Day 3: Nitrates between 2 and 5ppm, phosphorus at 0ppb. Dosed only phosphorus up to to 32ppb (0.098ppm) and fed a lot of frozen Mysis
- Day 4: Nitrates at 2ppm, phosphorus at 0ppb. Glass is DIRTY.

I don't have any cyano, dino or diatom issues in the tank. What am I doing wrong here? Any suggestions on how I can maintain more balanced nutrients? Should I throw a Clown or Damsel in here or something?

Vinny Kreyling

Premium Member
Van, with only corals I would pull 1/2 of the Marine pure gems.
Nothing to loose & I thing you might not even need any.
Your only bio load is 2 crabs & a shrimp.