In the meantime, the Ameca splendens in the greenwater tank don't mind the green. They may even appreciate the slightly better (lower nitrate & ammonia) water quality. A female looks ready to drop her 1/2 inch fry.

Clearly, or is that cloudily? different strokes for different folks. :)

Wouldn't want that in the other tanks though.

Green water is one of those things you get when you don't want it and can't keep when you want it! Lots of light, plenty of fish waste in the water and (get this!) nutrients from the new water in water changes all will help fuel an algae bloom.

Sometimes an hour or two of sunlight, each day, will help turn a tank green. I had a couple of small tanks (one guppy tank, one Endler's) recently turn green. They both seemed healthy despite the fact that "the joint was jumping." They almost completely cleared in the last two days. Except for feeding the residents, nothing was done to them.

My guess is that they have been lit up by the summer sun the last two months. As the sun's angle "moves" back south, it is no longer shining on them.

Most of the greenwater precipitated out. I need to vac those tanks when I get done with this note. I'll use the Guppygirl Narrow Tube Mini-Gravel Vacuum TM so no fry get pulled out. (Siphoning into a white bucket will also help spot fry.)

Green water is mostly made up of those microscopic protists (moving little animal like things with chlorophyll) which we read about in biology. Aged members of GL will remember them as protozoans - what they were called before they were given their own kingdom.

An inexpensive microscope at 30x will reveal a lot of wee creatures such as Paramecium, Euglena and many other one-celled and multiple celled creatures. Any introduction to microscopes book will show you what these look like (or an old biology book). All established aquariums have them. The light + nitrogenous wastes + the minerals in the water changes help them multiply in far greater numbers than usual.

Why do some of us actually encourage (i.e. struggle to raise) the stuff? I find it the safest - and one of the best - foods for Daphnia cultures. Some people have found a small greenwater tank will actually serve as a good hospital tank for a fish, which has gotten a little chewed up. Others will suggest that it may be beneficial to the growth and color of fry (if you don't mind not seeing them too much).

Indeed if you are going to raise tiny fry like those of the rainbowfish, lampeyes, ricefish, or Anabandids, you will have a lot more "luck" raising them in greenwater with a clean up crew of snails and light feedings of a commercial egg layer first food (APR, Tetra E...)

I would guess that it could be physically removed by a diatom filter, a canister filter with diatomaceous earth in it or maybe an already dirty sponge filter. Others here will have more experience in this area of microfiltration.

I have purposely killed it off by covering the top of the tank with a heavy carpet of floating plants. However I'm usually trying too hard to grow the stuff.

Interestingly, an article in an aquarium plant hobby magazine several years ago contended that greenwater actually will limit or completely absorb the nitrates!

If it dies off at once nitrate counts may go up. If the moribund green stuff on the tank bottom is not siphoned off, nitrates may go up again.
(If any other sign of trouble accompanies the die off - a dubious smell for instance, change out the whole tank.)

Sometimes there are small pockets of dirt on the tank bottom. You seem to do a great job of gravel vacuuming, but you might double check. You already are taking measures to limit sunlight.

(Just a white or vanilla paper taped to the sunny sides of the tank will do it. Newpaper could be used for the more literate guppies. Dark hued paper could absorb some heat).

Maybe feed a little less. Trim the population (easier said than done). Can you give some of those guppies back to your Mom? ;) Would a shop take any?

Note that limiting greenwater is similar to limiting algae. However there have been some amusing situations where the more a person partially changed water, the greener the tank got! So the treatments are not exactly the same. Limit animal generated nutrients, maybe population size, light, dirt in the tank and (somehow) the introduction of too many new minerals into the tank. ;)

Probably if you can cut a couple of those factors, the green will fade.

If you have the time, check out these previous GL discussions which touch on the topic of green water:

Algae  
By Geo3383
from the Geo3383 department, Section Diaries
Posted on Fri May 7th, 2004 at 03:50:58 PST

Need help with a green tank
By Scott Lockwood [Edit User], Section Ask Guppylog
Posted on Sun Aug 3rd, 2003 at 14:01:45 PST  

Major Algae Bloom  
By GuppyAdict, Section Ask Guppylog
Posted on Tue Sep 16th, 2003 at 02:26:13 PST