Green Water

[rtoomey]

Please Help! I have a 22,000 gallon IGB Vinyl pool. I cannot get rid of the green water. Pool shop has tested water and they told me my water is great but why is it still green. Tired of spending $ on chemicals that do not work.
Thanks,
Rob

[nick182]

Hello Rob,

I'm a newbie here and also at pool maintenance, but I am currently living the same situation as you (fighting resilient algae in an inground vinyl pool). I've read a bit on the subject myself and gotten some advice from fellow pool peeps, and I think one of the first question you'll get before anything is, what is the current chemical status of your pool? Pool store can tell you that the chem balance "looks great"', but they are sometimes wrong, or it might be "great" for maintenance but not for battling resilient algae.

If you look at my situation, my water is also pretty well balanced from a chemical standpoint (pH in the 7.4, daily Chlorine very high over 10ppm, alcalinity approx 100ppm, stabilizer approx 30-50 ppm), but water is still green. However, I know now that removal of massive algae presence is a battle that needs to be fought over several days and even weeks, despite great chem balance. Chem balance is one of the 2 essential pre-requisites. The other one being properly filtering / removing debris and waste: do you need to backwash often? what is the look of your water coming out? do you have sand filter? do you suspect that you still have lots of debris in the pool ? etc...

Finally, it seems like even with solid chemistry AND good filtering and work ethic on the brushing/scrubbing/removal of debris in pool and skimmer, algae presence needs agressive shock treatments with chlorine (preferably liquid chlorine.. ie. bleach). You'll need to go well beyond the normal chlorine levels that are necessary for maintenance. Usually, between 1-3 ppm free (active) chlorine is fine once the water is clear.... but with massive algae presence, we need to shock the pool often over the 15++ ppm level in order to kill this persistent green enemy. Note that the level of free chlorine necessary will depend on your pool chemistry (including the CYA / stabilizer level, which seems to be a key factor)

Good luck in the fight

[PoolDoc]

Most of what Nick told you is right on the nose. The key here is good testing. Read the test kit page in my sig; see if your local Walmart has an HTH 6-way drops kit, which is an excellent get-it-now option, if available.