Adrian, I usually have 20-30 gallons left in the tank when I finish spraying, and know I'll be spraying glyphos again in a day or three.  I hate to drain out a perfectly good mix that will be good start on the next batch.

Today I mixed a tank with AMS and before I added glyphos, it started to rain...........still raining,  so I don't know how long it will sit.  I think I'll back it in the shed to keep the sun off it.....if it come out.

Algae being a plant, I thought maybe glyphos would put the axe to it too, but apparently not so by the replies so far.

Cary, I got no problem draining this one dry, I just hate to waste the chems to beat the damn algae.