2nd round of Green Water

[mel]

Ok so here we go. We have recently bought a new house and thought we were going well with maintaining our pool when all of a sudden the rainy weather came along and the pool went green, we then took samples to the pool shop to get tested and got it all sorted and three days later it was crystal clear. We then made sure that the levels were always right and then two days later the rain came back and so did the green water but this time we can't seem to fight it. All the levels are correct and we have now resorted to sticking bleach in there to try and shock it that way. Any help on this matter would be greatly appreciated. Oh and it has been raining for the last 8days which is how long we being trying to get rid of the green.
FC: very high way over 10
TC: not sure
pH: 7.2
TA: about 120
stabilizer : 100
My pool: approx 55000litres, cement base,
Pool chemicals:liquid chlorine
My pump & filter: sand filter which may need sand replaced unsure thinking this may be a problem. sand is approx three years old
Other info: we are using liquid chlorine which is what the previous owners were using advice on chlorine types we are going to change to salt ones we get the money to.

[Larry]

I think the critical point here is the stabilizer level. 100ppm is a little high so 10ppm FC is normal. You should try to get the FC level up to 20+ppm to destroy the algae and maintain the level at no lower than 5ppm after the algae has cleared.

An algaecide will help keep the algae away and after each rainstorm you should add some extra chlorine (before the sun comes out if possible) to compensate for the extra dirt load introduced by the rain.

Liquid chlorine or bleach are both suitable, as is cal hypo (HTH or similar). Dichlor, trichlor and tablets are not advisable as they will increase your already high stabilizer level.

Larry

[samueltt]

bleach is low concentrate liquid chlorine.

liquid chlorine is typically 10%-14% and bleach is 3%-6%