Alga in a grow is NOT GOOD at any time any place. It's a minor problem yes but a problem is still a problem and should be corrected. It's an early sign of other problems that have not showed them self yet. It should be corrected as soon as it's noticed. The source should be found and corrected. Sometime it's as easy as sand on top of your soil to keep the light out. Or in hydro we use net pot covers until the leafs are large enough to cover the grow rocks.

GK you are the one who was complaining in the lounge about information not being correct.

Just thought I would correct some minor miss-information.