Lighting and algae?

[asylumdown]

do they get tiny bubbles in them by the end of the day? If they're brown and stringy to me it sounds like dinoflagellates but you'd need to confirm that with a microscope.

There's a bajillion different kinds of dinos, some are horrific, toxic, poisonous and just generally awful - think red tides and shellfish not suitable for human consumption, and some are just unsightly and darn persistent but otherwise seemingly harmless. Hard to know which one you've got, but if all of a sudden all your slime eating snails like Astreas suddenly kack it en mass there's a good chance you've got one of the less friendly kinds.

I also wouldn't be so quick to link it to the lights. They can happen regardless of your lighting system and are known to occur in tanks lit by pretty much every kind of technology in the trade.

ETA just re-red your initial post and you said they do in fact get bubbles. That to me sounds like dinos. The most obvious time to look for them is on your rocks at the end of the day right before lights out. If you look at an oblique angle you might see a fine layer of microbubbles covering your rocks. Classic symptom of dinos