Will phosphates hurt anything?

[ozorowsky]

Hi all,

My tank is about 6 weeks old, and has brown algae growing. My phosphates per my API test kit are 2.0. I jumped the gun a lil added some fish/corals; all seem happy/healthy so far, but I'm worried about this brown algae.

I don't have any ammonia/nitrites/nitrates, just my phosphates are really high.

Thanks!

[nereefpat]

They just can cause algae problems, and there is some evidence that high levels (your's would be very high) slow down coral growth.

Nothing a few water changes couldn't solve

[bertoni]

I might get a second opinion on the test kit before spending a lot of money. 2 ppm is very high, and I agree that it might affect stony corals and coralline. Otherwise, if the tank is doing well enough, with no algae problems, you could ignore the level.

If you do water changes to remove phosphate, keep in mind that the sand and live rock might have adsorbed a lot of phosphate. If so, the level might bounce up very quickly after a water change. You could look into a GFO (like RowaPhos, PhosBan, or the BRS bulk products) as a cheaper approach. Lanthanum chloride is even less expensive, but it's more trouble to dose since it forms a precipitate that should be removed with a filter or net.

[dkeller_nc]

As Jonathan is alluding to, colorimetric test kits for phosphate that require you to color-match the test solution to a test card are not very accurate, nor sensitive.

That's why you see so many in the reef hobby using Hanna phosphate checkers. The same basic reaction is occurring in the test solution, but the Hanna test uses a photodiode to illuminate the sample, and a photocell to measure the amount of light coming through the sample at that wavelength. A setup like that is vastly more sensitive than our eyes, and allows reefers to maintain an "ideal" phosphate concentration of around 50 ppb.

But - your tank is far too young to really need the Hanna phosphate test. A much better plan would be to initiate a schedule of regular water changes of about 20% per week, make sure that you're not overfeeding your fish (which adds phosphate), and use highly purified water (RODI) to make your saltwater for water changes and water for evaporation makeup. Generally speaking, municipal water is relatively low in phosphate, but that's not true in all areas of the country.

[bertoni]

Yes, given the age of the tank, a few water changes likely will improve the situation fairly quickly, if the phosphate level doesn't drop on its now with growth. I might try 3-4 20% changes, maybe one a day, and work from there, or I might wait to see how much phosphate the algae can consume.

[ozorowsky]

Thanks all! So you don't think my fish/ corals are in jeopardy?

I'm not opposed to buying gfo reactor but don't know if ishould buy bio pellet reactor or gfo reactor or they the same thing? I would need one for a340 gallon setup as that's where these fish are going once its ready.

[bertoni]

The fish won't care about the phosphate level at all. The corals should be okay in the short term. I'd worry if they started showing signs of trouble. Since the tank has corals, though, I'd definitely start some water changes today. Are they stony corals, or soft corals?

[ozorowsky]

All soft minus a favia

[bertoni]

Soft corals will tend to do better with phosphate than the Favia. I'd probably start some water changes, out of caution, but I'd do 15-20% at a time, maybe once a day. Twice a day might be appropriate if the Favia (or other corals) start showing signs of problems. You could consider running a phosphate binder like PhosBan, as well.