I have recently purchased an established (about 1 year) 29 gallon nano reef. I used mostly the water that was already in the tank and have done one 5 gallon change so farwith Corallife salt. The previous owner used Corallife salt and so I did too for the first water change. Here's my problem ...
I tested the water for phosphates (I have 2 kits a Seachem and a Seatest both of which I read aren't great). For the first 4 days I noticed great readings on both kits < .2 ppm
I top off with RO water from Galcier water machine outside grocery store (I don't have RO/DI unit yet and nobody seems to sell RO AND DI bottled here) daily. Since day 5 the phosphate levels steadily climb and are now at @1.5 ppm. Easy enough right? Must be the RO water used for top offs. I test that water and it is <.2.
I test the fresh salt mix water and it is < .2. I have no sign off hair algae, yet but I do have 2 mithrax crabs, several types of hermits and several types of snails. I have no fish and only a leather coral, a bubble coral and some green button polyps
for corals. I have a couple types of Caulerpa that are growing at what I consider normal rates. I am seeing some very slight signs of green algae growth on substrate and empty shells, etc. My other parameters are:
pH 8.0 - 8.1
temp 80 - 81
calcium 430 - 480 (depending on test kit used)
The only thing I add is DT phytoplankton every other day at recommended dosage.
So what else can cause such high phosphate levels
that seem to be climbing?
The reason I mention the Corallife salt is I have read it is notoriously high in phosphates but I don't get bad readings from mix that I aereate for 3-5 days before water change.
I also tried a Poly Filter for about a week. It turned brown but the phosphate level didn't drop at all.
Sorry for the long post. Thank you!