Can I do this? SWG and Chlorine?

[bcrumb]

I have the standard T15 cell and it was just replaced last year. The pool is 28,000 gallons. I will post the numbers later as I am not home right now. Best I can remember my CYA is only at around 50. I thought I should keep it as low as possible because last year I had an algae problem and had to raise the chlorine to around 15ppm (per instructions found here) in order to clear it. I thought the higher the CYA, the higher you had to raise the chlorine level in order to kill the algae. I use a DE filter, Aquarite SWG. When the Cell went bad last year, I had to call Goldline(Aquarite). They told me that I should expect to have to run the SWG at 90 percent or above and that 12 hours would be the min I chould expect to get away with. Most times when I check the FCL, it is only around .5 to 1.0 ppm.

[bcrumb]

Forgot to say the salt level is good at 3200. Also, If you go with the 2 speed pump, what determines whether low or high speed is selected. You don't need a new timer/control box do you? I assume the pump itself has some sort of control device to select the speed and times.

[CarlD]

Nah, mine is simple: there's a toggle on the back of the motor. That's been good enough for me for 7 seasons, so far.

Rule of thumb: Low is normal, High is for vacuuming, backwashing, aerating, or when I want to get the most out of my solar panels.

[waterbear]

I have the standard T15 cell and it was just replaced last year. The pool is 28,000 gallons. I will post the numbers later as I am not home right now. Best I can remember my CYA is only at around 50. I thought I should keep it as low as possible because last year I had an algae problem and had to raise the chlorine to around 15ppm (per instructions found here) in order to clear it. I thought the higher the CYA, the higher you had to raise the chlorine level in order to kill the algae. I use a DE filter, Aquarite SWG. When the Cell went bad last year, I had to call Goldline(Aquarite). They told me that I should expect to have to run the SWG at 90 percent or above and that 12 hours would be the min I chould expect to get away with. Most times when I check the FCL, it is only around .5 to 1.0 ppm.

You need to run the CYA at about 80 ppm and keep the FC at about 4 ppm. Also lower the TA to about 70 ppm. This combo will insure that your maintain adequate FC in the pool without problems and give you better pH stability than you have now (it will lower your acid demand since it will allow you to GREATLY reduce the cell output). I doubt you will be able to reduce the pump run time below aabut 8-10 hours but I suspect the reason you cannot maintain chloirne is a nascent algae bloom. Shock the pool to about 20-25 ppm and I think you will find that the chlorine will start holding once you get your other water parameters in line with my suggestions.