SLAM & pH Question

[440dodge440]

Hi,
I'm currently running the 3" tablets through an auto feed chlorinator. I'm not registering any chlorine. I want to do the SLAM method and switch to liquid chlorine, but my CYA is <20...Do I need to bring the CYA up by adding stabilizer first, or can I SLAM at the low CYA level? I also need to bring the pH up from 6.8, but I'm not having luck seeing a change after adding pH up and then two boxes of Borax...should I just keep adding to bring the pH up, or is there another potential problem?

Thanks

 

[JasonLion]

The minimum CYA level for doing a proper SLAM is around 30.

The standard PH test will report any PH below 6.8 as 6.8. So there is no easy way to tell just how low your PH actually is. Trichlor tablets are very acidic. When using them you need to constantly be raising the PH. If you haven't raised the PH in a while, it might take quite a bit of borax to get the PH back into range.

 

[440dodge440]

Thanks....I added some stabilizer a few days ago, but I'm backwashing the DE filter every day- the pool was closed I August (we moved here in November), so there's a good bit of dirt.etc, but now the water looks pretty clear. Should I wait until I stop needing to backwash so often before adding the Borax and stabilizer? Any recommendation on how much Borax and stabilizer to add at one time before retest? I was following the Pool School Calculator, but it sounds like I may need to stray a bit from that.

 

[JasonLion]

You want to work on raising the PH soon/first to make sure it doesn't cause any problems. CYA could wait if it needs to.

How much borax to add at one time depends on your TA and Borate levels (if you never intentionally raised borates, just assume it is zero). You can use PoolMath to calculate how much borax to raise the PH from 6.8 to 7.5 given your TA and Borate level and then use that much. Keep in mind that TA may change each time your raise the PH, so needs to be retested and then the quantity recalculated.