UK Pool opening - unexpected test results in my SLAM


Jun 1, 2019
Hi all, hoping i can get some experienced guidance as to which way to go from here...

UK based, started pool opening a week ago. Vac'd to waste, brushed, tested and everything was looking good in terms of its ph, Alk and CYA. So I started to SLAM by dosing with 10l of 15% liquid chlorine. That seems to have done it's intention on the algae and i've a clear colour (if a little cloudy set of water). So, my quandry... Alkalinity had dropped below target range according to Pool Math (down to 17) so i used 5kg of Sodium Bicarb.

Free Chlorine is now measuring above the range of my ColorQ and has been for three days now, pH is in range, TA is 30 and CYA is 21.

Is my next step to load up with more Alkalinity Builder?



Mod Squad
Gold Supporter
Platinum Supporter
LifeTime Supporter
Jul 16, 2012
Central MD
Pool Size
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
If your water is still cloudy, you should follow the SLAM Process through to its conclusion disregarding any measurements except FC until you are finished. It is complete when you have crystal clear water, CC of .5 or less and you pass the Overnight Chlorine Loss Test.


In The Industry
Apr 1, 2018
Bangor Maine
With a SWCG you want to keep alkalinity lower than normal, say 50-80 because salt pools tend to drive the ph up, keeping alkalinity low helps reduce the ph gains a bit.