Help with green water

[jerry5757]

Could use some help and feedback here. First time in 8 yrs. of pool ownership that I'm loosing the battle.:(

IG 30,000 gallon pool had been great so far this year; with the info here finally understood how to bring TA down and bring pH back up. Water had been crystal clear. Used only acid and bleach, along with aeration for the pH. Some loss of water do to an under-decking leak and evaporation; refill with high TA well water probably less than 1/2 inch per day, but TA regulary adjusted with acid.

Problems began failure of my Polaris pool cleaner which allowed what I believe was a combination of dirt, sediment, and algae to build up on the bottom. Finally got past my disdain for vacuuming and got to work. Vacuumed what I could and then brushed everything again figuring (sand) filter would pick up the rest.

Since then the water had been a light lime green and unrespondent to chlorine at varying levels. Last night added some old shock (4 in 1) I had around and checked levels 3 hours later: ph - 7.5; Cl - 8; TA - 100 (Cl measured by diluting pool water to 25% with non-Cl tap water, testing, then multiply by 4). Assuming almost no CYA as I haven't used it and just started using my chlorine feeder with tablets only 2 days ago, but not really sure all what is in the 4 in 1 shock as far as CYA.

After measuring I added about 5 gallons of 6% bleach, which based on my calculations should raise Cl 10 ppm to a total of 18. Went to bed, too late for waiting for mixing to measure. Didn't test this morning, long day at work, hot day with lot of sun, water still green tonight, tested again and numbers essentially back to same , level as before adding the bleach (pH 7.5, Cl 8, TA 100). Put another way, it appears my pool gobbled up the 5 gallons of bleach in the last 24 hours:confused:

Questions and looking for feedback on:

Assuming algae, just how high do I need to go with CL? I've never had this lack of response, and in past years always was able to easily bring algae under control
Are my assumptions on testing high chlorine levels correct?
What direction do I need to go in to get this under control? Any other ideas?
Could this be anything else? The water doesn't appear dirty, just discolored and cloudy, and the sides haven't "re-greened" since the scrubbing,, but there's not much else it could be in my book.


Pump and filter has been on 24/day last 4 days with minimal need to backflush. Water temp up the past week from 78 to 85F with daily air temp in 90's.

Thanks in advance for any help.

Jerry

[TRHOD12]

Jerry,

I'm ,by no means, an expert on this. But I did sleep in a holiday in express last night:) . (Sorry, wanted to start with a little humor)

I just this past weekend went thru this same thing.

From what I've read and what I've experienced you will need to keep your shock FC in the 15-20ppm range till the algae clears. I know this is dependant on the amount of CYA that is in the pool, but it seems like you're just not maintaining enough FC to kill the algae. I didn't see what your CYA level was. What is it?? That will tell you where your shock level FC should be at.

In my recent episode with algae I was testing three times a day, and was loosing ALOT of FC thru out the shock phase. I'm talking 4-8ppm in a 5-6 hour period. So yes, to answer your question, your pool could have been using up the entire bleach that you added.

You've got to get the FC high, but it seems, most importantly you need to maintain this high level UNTIL THE TC HOLD OVER NIGHT. This is important. I say TC here and not FC, because from what I understand, after you shock to the appropriate level there should not be any CC.

With my pool, the pool cleared up in about 1 1/2 days, but my chemistry was still telling me that the FC was fighting algae. I was still loosing 2-3ppm over a 5 hour period. This went on for another 24hrs. I maintained the shock level, and over night the TC held. This told me the algae was all gone.

Be patient, be persistant. Keep the shock levels up, do not let them drop below 15, brush and vacuum (I did twice a day). It should clear up.

I hope this helps, and I'm sure others more in the know will chime in and help you out. This is by no means a "gospel way to cleaning algae", just one newbee's recent experience with algae and my limited knowledge on the subject.

BLessings,