how to safely drain pool

[Kim S]

My CYA levels are too high, and I need to fill and drain the pool. I know to do this safely I should do this in steps, and never completely drain the pool. I read on previous posts that one can take the water level several inches below the skimmer. What happens if I let water level go below the skimmer weir level? Will the pump lose prime and burn out? I have a handle near the intake to the pump, and I can completely turn off one skimmer, but not both.

Also, is there ever a need to backwash a cartridge filter? On the outlet valve leading from the filter, I can turn the handle to "cleaner" (vs. to "pool") but I am not sure what this does. There is a guage on this part of the pipe as well. I inherited the pool when we bought the house, and was never sure about this. Thanks!

Pool Specifics:
IG gunite; 15,300 gallons; cartridge filter; no spa; Houston, TX
FC: 5ppm
TC: 5ppm
pH: 7.4
hardness: 230ppm
Alk: 80
CYA: 100-120
copper: 0
Iron: 0
TDS: 500

 

[Guest]

you have a dedicated pressure cleaner port in your pool, don't you? The valve controls how much water goes to the normal returns and how much goes to the cleaner port. It has nothing to do with backwashing and you do not backwash a cartridge filter.

From th setup of your plumbing it look like you do not have a main drain in the pool. If so then the only way to drain the pool is with an addtional pump such as a sump pump or submergable pump such as used in ponds.

Also, if you resize your pics before posting them to a smaller size it would make your post much easier to read.

 

[JasonLion]

No, there is never any need backwash a cartridge filter, and if you did it would damage the filter. Your system doesn't allow you to backwash. You take the cartridge out and hose it off instead.

To drain below the skimmer you need to use a vacuum hose. It is best to also get a small pump pumping water into the skimmer area to prevent any small leaks from causing a loss of prime.

It takes more fill water, but is simpler to just drain at the same time you are filling, keeping the water level about where it is. The net effect is the same and for 50% or less water replacement the extra water required isn't too bad.