Help with Chaeto in Fijicube 20 Sump

[NS Mike D]

I think you are probably correct. I measured my P03 and it was essentialy 0 ( hard to tell using API test kit). I am not sure what the right solution is to that. I think this negligble phosphate levels may also be negatively affecting my zoas ( they are shrinking ). If the best way to increase phosphates to feed more and skim less?

API NO3 and PO4 kits are generally consider not sensitive enough for reef tank purposes. Other options off the top of my head are Hanna, Red Sea, Sefeirt, NYOS etc.

These are very useful in our hobby.

Get a good hold of your NO3 and PO4 numbers and what range you to maintain. Red Sea recommends 1-2 ppm for NO3 and 0.08 - 0.12ppm for PO4. Personally, I think the NO3 number is a bit low, probably good for new tanks, but NO3 creeping up with age is OK. I like the PO4 range. Some folks like to go real low, but IMO thats threading the needle a bit and too low with either is a recipe for problems

If you are low on NO3 and PO4 dial the cheato lights and run the skimmer on a timer. Find a nice balance as these to will both lower NO3 and PO4 but in different ways removing different things.