I am new to this forum, however I have been a pool owner for 43 years and have owned my current pool for 39 years. I have maintained my pools—pool chemistry, cleaning, etc. myself during that time. I live in Southern Calif. (Orange County).
During the past two or three summers, I have experienced an algae problem that I never experienced before. Green/yellow algae on the walls (plaster pool), need for constant brushing, filter plugging and backwashing, sanitizer usage, etc.
After a lot of reading and research, I came to the conclusion that my problem was high CYA levels combined with too low levels of FC (2-3 ppm). I was carrying CYA levels of 80-100 ppm, (recommendation of pool store) or more, and using tri-chloro tabs for chlorine stabilization, not realizing that was also increasing my CYA (the past year, I have stopped using the tabs and now use liquid sodium hypochlorite). According to the info on this website, and others, the higher the CYA levels, the need for higher FC to afford good protection.
In the last two or three months, I have strived to get my pool in proper balance (pH, TA, FC, CYA, CH). I drained nearly 1/2 of my pool (and this is a problem since I am in a drought zone and constrained on my water usage). Here are my current pool metrics:
CYA 60 - 70
CH 800 (I realize high but again constrained by drought situation)
As I write this my pool looks great. But with summer approaching, I am dreading the return of my algae problem. According to the info on this website, with a CYA of 60, I need to maintain a FC of 5ppm. With this background info, I have a few questions of which the first is the most important.
- Assuming my hypothesis is correct about the relationship between CYA/FC/Algae, do I need to bite the bullet and maintain a 5ppm FC this summer to avoid an algae problem? It will require a lot of liquid chlorine (and acid since I believe that sodium hypochlorite raises pH and low pH enhances chlorine’s effectiveness). I am willing to do this unless there is an alternative I am not aware of. Is a FC of 5 safe for swimmers?
- During the last few months in which I mentioned earlier that I was trying to achieve proper pool chemistry balance, I have added a lot of acid. Originally my pH was 7.8+ and the TA was 100 or higher. Every other day I check pH, FC, TA and acid demand. I am adding on average 3 pints of acid every other day (38,000 gallon pool) with no change in pH or TA. (As mentioned earlier my current pH is 7.6 and TA is 90 but seems to be stuck there). The only reason I am adding acid is because the acid demand test indicates a need for it. Am I on the verge of a huge breakthrough in either pH or TA or is something else going on?
- I do not understand why I have not experienced this algae problem in all the years I have maintained my pool(s) except for the last three or four. Any insights on this?
- Does the high CH have any bearing on any of this?
- Is it necessary to shock a pool on a routine basis? I was using a shock product (di-chloro) on a minimal basis the past few summers, more as a clarifier and floculator rather than a chlorine agent. Should I shock even if I do not have a visible algae problem (keeping in mind that de-chloro, I believe, increases CYA).
I realize this may be a lot to digest, but I felt compelled to provide as much background info in order to reduce the amount of guessing on my situation.