Twenty litre tank, neocaridina, set up in July. I have been scraping the glass and the hardscape clean every weekend because I assumed that was the job, and the shrimp seem less busy than they were.
Meanwhile a friend's tank looks filthy by comparison and is full of shrimplets. Is a clean tank actually worse for them, and is there a point at which algae stops being food and becomes a problem?
The two levers that actually work are light and food, and both are free. Put the light on a timer at something like six to eight hours a day, and feed less than you think: shrimp eat astonishingly little and uneaten food is what fuels the growth you are scraping off.
Add fast-growing floating plants to compete for nutrients, keep up small regular water changes, and pull hair algae out by hand. That is the whole toolkit.
Brown diatoms in a tank this young are normal and usually fade as it matures. The shrimp may eat them.
Two things that will cost you the colony rather than the aesthetics. Do not use algaecides or any treatment that is not clearly labelled shrimp safe, because a great many aquarium products are dangerous to invertebrates. And read ingredient labels for copper specifically: it is highly toxic to shrimp and it turns up in medications and algae products.
Also worth knowing the one that is not algae. Blue-green algae is cyanobacteria, a slimy dark sheet that peels off in layers and smells unpleasant. Shrimp do not eat it, it smothers things, and it usually means poor flow or decaying waste. Siphon it out and fix the circulation.
@biofilm_is_lunch · 6d ago · 3 replies
You have been removing their food every weekend. Dwarf shrimp graze more or less all day on biofilm, the thin layer of microorganisms and algae that grows on every surface, plus soft algae on plants and rock and glass. For shrimplets especially that is most of the diet.
So a spotless tank is a worse home than one with a light coating of growth. Keep the back wall and a rock or two uncleaned on purpose, scrape only the front pane, and stop apologising for the green.
Reply
Report
@scrubbed_it_clean · 5d ago
Where is the line then? There must be a point where there is too much of it.
Reply
Report
@biofilm_is_lunch · 5d ago
Algae rarely harms shrimp directly. Heavy growth is a message about balance rather than a danger: too much light, too many nutrients, usually both. Worry when it covers plants thickly enough to shade them, when hair algae forms mats that can trap shrimplets, when the water itself goes green, or when it grows straight back after cleaning.
Reply
Report