mavs215 said:
We have a chlorine machine that makes chlorine from salt. We have had this for about 5 years with no problem and have just had it serviced. The chlorine it makes is unstabilized so I add stabilizer. That said, heres my problem. I've got a stain on the plaster that is a dark yellow. It has not responded to three algaecide treatments. I have taken a full set of readings, keep in mind the CH is not usually so high, I've increased to fight the stain. Thanks for any advice.
FC 5
TC 8
CC 3
PH 7.2
TA 80
CH 850
CYA 140
PHOS 325
Welcome to the forum...
Your machine is an SWG, you should list that equipment in your signature.
Algaecide doesn't have any affect on stains. Algaecide prevents algae. Once algae is present, the best way to kill it is shock levels of chlorine. Adding too much algaecide can cause more harm than good, especially if you used linear quat based or copper based. Can you tell me what the active ingredient of the algaecide was?
Your first step in stain treatment would be do determine if the stain is metal or organic. To check for metals - read
this article here.
To check for organics - hold or weigh down a trichlor tablet on the stain for 30 min, and see if it fades.
If the stains are copper, neither of the above will remove the stain, the vit C may actually darken it.
I can tell you your numbers are really out of whack. What test kit are you using?
See the article in Pool School
water balance for SWGs and also
Recommended Levels
Your CYA is too high, you want it at 70-80. Your Calcium is way too high. I'm not sure why you felt raising the CH to 850 would treat the stains? (it doesn't).
I'd suggest a partial water replacement to lower both of these numbers. See below.
Ignore the phosphate reading it's irrelevant.
I'm wondering what is causing the CC to be 3? You don't want your CC to be above .5, if it goes above .5 we recommend you shock your pool. With your CYA so high, shocking isn't very practical (see the CYA chart).
With an SWG, once your stabilizer level is at 70-80,
you don't need to keep adding it. With a cartridge filter, you don't lose the CYA level as quickly as one would with a sand filter thru backwashing.
Assuming these numbers are indeed accurate, I'd suggest that you consider draining about 50% of your water and replace it with fresh. This is the only way to lower the CYA and the CH. This will require all your other numbers to be readjusted, including your salt level, but right now you are headed down a path of trouble.
Is draining 50% of the water in your plaster pool possible in your particular situation? Otherwise you may have to do a series of partial drains and refills, say 1 foot down, refill, recirculate, repeat. Do you have any watertable issues in your area?
I know this is alot to take in, and it's really frustrating to have 5 successful seasons and then suddenly a lot of trouble. But it seems to me this has been building for awhile. IT's not going to be fixed overnight, so be sure to have plenty of POP - Pool Owner Patience.
Hope this helps.
.....got a pic of this?
