Re: What stopped them?
> Then light green hairy algae took over
> the tank, not attached to anything in particular. I thought that I would let
> this grow to take out as much of whatever there was an excess of fronm the tank.
> The higher plants as I say have stopped growing, and they are now a lighter
> green than they should be except the eel grass which, where it is still alive?
> is nearly black.
Your problem could be iron defiency. The symptoms are, normally
that new leaves are yellow and later the plant stops growing.