Green Water

[Donya]

My 5-gal pico's water turned green overnight (clear to opaque in roughly 6 hours)...but 4-5 hours later it's thining to not being very cloudy at all, although it still has a green tint. Recent events:
- 2 or 3 days ago, 10% water change. New mixed water was from distilled water.
- yesterday: 0 ammonia, nitrite, and nitrate, pH 8.2.
- this morning when opaque green: 0 ammonia, nitrite, and nitrate still and no pH change.

Animals/macros:
-1 Gobidion okinawae
-baby conches, nerites, etc. and a hermit crab
-lots of Caulerpa

Possible things I can think of that caused it or may be related:
- the distilled water? Should have been phosphate/nitrate/etc. free, never had trouble with that from the salt either. The bottle of distilled has been used for the last 3 weeks with no troubles.
- something could have died, although I can't find evidence and all animals are accounted for.
- maybe I overfed the goby last night, although the amount wasn't more than I've put in before.
- perhaps the Caulerpa did something bad? It all looks fine...no obvious dead/decaying sections.

I can't figure out offhand why this showed up so quickly, is dissappearing so quickly (that's the part that really confuses me), and isn't affecting the water params. When I've seen water color changes before they sometimes happened fast but took a lot longer than a few hours to start going away.

 

[steelhealr]

Chemical reaction? Although...don't know why? Did any of your green corals bleach? SH

 

[SkiFletch]

Have you or can you test for phosphate? Maybe it was some kind of phyto bloom

 

[Donya]

No corals in the tank, so it wasn't that. I will try to get phosphates tested tomarrow. I did catch one giveaway though after the first post: drop in dissolved O2 coinciding with the clearing of the water. I noticed my goby "gasping" every few seconds, put a bubbler in, and the behavior dissappeared within minutes. Water params were still fine after the bubbler. May well be a bloom of some sort...if there's any left when I get home I'll see if I can pop a sample under the microscope.

 

[Donya]

Well so much for figuring out what was going on. I got home and everything was crystal clear like nothing had happened. I couldn't get the phosphates tested today; I need to find a place that actually has the kits for sale or order one online.

 

[SkiFletch]

Marinedepot was way cheaper than my LFS

 

[Donya]

Thanks for the tip; I think I'll try to order more than just the phosphate kit if I can't find it locally...shipping makes one test kit double the price lol. I probably have enough stacked up things to get that I can't find locally though to warrent the shipping though.