Red Phytoplankton?

[joejvj]

Has anyone heard of or seen a tank with red cloudy water?

I have a 20 gal tank setup mainly for quarantine. It is heavily populated with fish at the moment, and I suspect it has a high level of organic compounds.

The water has turned a red, cloudy color. 50% water changes will dilute it, yet it comes back within a day or two. It does not seem to be harming the livestock. The tank has a skimmer, carbon, and bio-wheel filter. All standard water parameters are within acceptable ranges.

This does not look like a typical heterotroph bloom, as the water is definitely red in color. Interestingly, there is no mats or strings of red cyanobacteria in the tank.

I put a water sample under a microscope can see clusters of single-celled animals, similar to nanochloropsis in shape but much smaller in size. The clusters contain maybe 10-20 cells each, with the total width of the cluster around 20 microns.

Anyone seen this before?

[futrtrubl]

Could well be a phytoplankton bloom, a la "red tide". Not nescesarily harmful, but there is a chance they could be highly toxic (sometimes not to your residents but more often it needs to bioacumulate to show effects). If it's an ok phytoplankton then it could be good for your filter feeders. HOWEVER, check your nutrient readings, this may indicate a problem there.

Edward

[joejvj]

The fish will only be in there two more weeks (they are just newcomers in isolation). Everything else in the tank is inert.

If it is a variation of "red tide" the protein skimmer may be providing enough oxygen to keep things stable. I do not have the means to measure organic levels, though nitrate/phosphates are expectedly high due to the fish load.

[futrtrubl]

An oxygen crash is not the only thing to watch out for. Some of the nastier phytos can secrete toxins that can digest/kill fish and inverts. Pfiesteria piscicida types.

Edward

[bertoni]

There are many red phytoplankton, I think. Someone in the breeders forum mentioned culturing one of them as a food source. The treatment shouldn't be any different than for a green phytoplankton bloom.