The algae nutrient I'm using is this: https://www.amazon.com/gp/product/B00PB ... UTF8&psc=1
I have one tank that is less than 1/2 gallon, and another a bit more than a gallon. Both populations have only lived off tank algae since January (the ones in the smaller tank) and March. Neither tank started off with any overabundance of algae. Three shrimp of the original ten in the smaller tank berried and produced larvae last May.
My current program to nourish the algae is to do it at the time I need to top off the water in the tanks. At that time I do any glass cleaning and scraping that is needed, fill with distilled water, and then add (for the larger tank) 1 drop of the nutrient, and to the smaller one a drop of a diluted solution so it gets 1/4 drop of the nutrient. It's looking like this will happen 3 or 4 times a year. So far this seems to produce a very slow hazing of the glass that progresses over several months and stays ahead of the shrimp's ability to eat it. I have no snails.
One thing I've noticed, and someone may have insight on, is that for many months I have not had any biofilm except for some tiny patches in the larger tank. I did notice that when I have intervened in the tank (which was happening a lot until last summer), the activity tends to decimate the biofilm, and it never really has come back. Should I expect if there were more nutrients in the water, it would re-form? If so, I may be at a good balance where the shrimp have enough to eat but there's no scum on the top.
The picture below is the smaller tank, which I think I got in March or April. I moved my original shrimp batch into it (they had formerly been in the larger tank pictured further below that now houses my more recent shrimp batch). This is a 5X5 inch cube (external measurements).
This one may give some indication of the algae haze. I've never scraped the glass of this tank, but there is no problem with visibility:
Because of the smaller gravel size now in this tank, I can give the shrimp a treat by using a long, thin rod to stir up a small area of the gravel, which is 1/2 inch deep, max - and soon most of the shrimp are gathered there chowing down on the newly exposed food.
