Just new to the site. We have a 35,000L (just over 9,000USG) in ground pebblecrete pool which is about 6-7yrs old. Equipment is an Autochlor S30 SWG with chlorinator set to 'LOW' (can't find out how much the cell actually generates per hr), 18,000Lp/h pump & cartridge filter. At the moment it's winter up here, so the system is on 3hrs am and 3hrs pm. Pool is in full sun and still gets used, (daytime air temps around 28, night around 15deg, pool is a steady 20-23deg) but nothing like the bather load in a usual summer where the system is set for 4hrs + 4hrs. Returns are in-pool surface directed, so no other aeration than that.
We've just bought this place a month or so ago - so just getting used to the pool etc. Testing was done by a pool guy up until now, so my first lot of test results showed pH off the scale past 8.2, TA 190, Cl off the scale past 5. We did have a fair bit of rain recently which added a good 3 inches to the level, so the pH rise wasn't unexpected.
Sampling at the local pool shop today shows:
Total Cl 8.0
(Free Cl 5.0, Comb Cl 3.0) There is that definite chloramine smell about the water...
pH 7.9 (I added a litre of HCl after the initial test result of >8.2)
Ca Hardness 100
Clearly the pH/TA needs addressing (pool shop reckons almost 3L HCl). But what about the Cl? The suggestions from the shop were to switch off the SWG for a few days and retest, but I'm not so sure about that. I can't seem to get my head around the chemistry, is this overchlorination by the cell, or too much combined Cl needing shocking? Do I need to stop the SWG for a while and turn down the running times?
There's obviously been no CYA for a while either, so I'll stick a few kg of that in soon, but what difference will that make to the results? I've seen some posts on here about borate - would that be useful?
Basically it would be great to get your ideas about what's actually going on chemistry wise, as well as what to actually do about it.
Regards from the Tropics, Stuart.