Hi all -
We're brand new to the forum and found it because of a problem we've been having - hope we can get some advice. We have a 30,000 gallon Desjoyaux inground vinyl pool with the frog mineral/chlorine system. We opened late this year and had a significant green algae problem to start - finally got it to go away (apparently) with shock, algecide and filtering. But our water stayed cloudy and all of our testing (test strips and pool store) showed 0 for both free and total chlorine over multiple days.
We were finally told about the "chlorine demand test" that a couple of companies do - we went to Bioguard and they told us we needed to add approx. 20 lbs of chlorine (using their burnout product). We were a little shocked at the price, but found a sale on liquid shock at another pool supply store (Namco) and basically added that much chlorine in liquid shock.
That evening, we also found this webpage and read about the correct approach to addressing this problem - i.e., adding bleach or shock to a desired free chlorine ppm level, and keeping it there until the free chlorine overnight demand test shows no decline (anyway, that's how I'm interpreting it). So we went ahead and continued adding bleach for the next day and a half using test strip estimates and the pool calculator (we also ordered a test kit - the TF-100 - it arrived yesterday afternoon).
Based on our initial test yesterday evening, it looks like we've been achieving a lot higher free chlorine than we needed to - our first test result last evening was 48 ppm (I actually diluted the sample with half pool water, half distilled so I wouldn't use up all the reagant too quickly). Our test result this morning (using same dilution method) was 52 ppm - I'm assuming the slight difference is inconsequential considering the dilution approach, so basically we're concluding our free chlorine showed no drop overnight. (To explain how I've been diluting - I use 5 ml pool water, 5 ml distilled water as a test - then I just go with the number of drops of reagant used, rather than dividing by half).
So we're tentatively (hopefully) thinking we've overcome our chlorine demand issue - however our pool water remains cloudy - it's a whitish cloudy, and when I clean our bag filters off (the desjoyaux pool uses bag filters that you can pull out and hose off) I see a whitish stuff that basically has the consistency of a runny mud or something).
What should be our next step? We're thinking we're done with adding bleach at such high levels for a while - but wanted to ask the experts. Our current levels this morning are -
ph - 7.4
FC - 52 ppm
CYA - 80 ppm
TA - 120
Again, last night our FC levels were 48 ppm - since I'm doing a dilution of the test sample, I figured the differences were inconsequential. Also, we didn't worry right now about testing for calcium - we have an inground vinyl pool.
Anyway, we appreciate all the information we've gotten so far from the webpage - I feel I know a lot more now about what's going on than over the past 4 years we've had the pool. In the past, the pool has actually been pretty trouble-free; this is the first major "crisis" we've had to deal with. Thanks in advance for your advice.