OK moved over to this forum for TA help

I have gotton much good info from a thread on another topic. I wanted to bring over here. Long story short- Let my Cl get low, started to get a little slimy algae- TA was around 40-, PH high. Added 14 lbs baking soda. Numbers were:

FC- 5.0
TC- 5.0
PH 8.0
TA 110
Hardness 190
CYA 40

No sparkle to the pool kind of cloudy looking.

To kill algae I raised CL to 15. I have been in the cycle of rasing with Baking soda (since TA was at 40) then lowering with acid.

Oh yeah 30,000 gal Salt water pool, vinyl lined.

This morning-
CL 13-15
TA 70
PH 8.0+

I know a salt pool will raise ph, but it's swingiong wildly- look at my TA over a 3 day period- 110 to 70. No wonder I have no sparkle! I run pump 24/7. I put in 1/2 gallon of acid this morning per the calculator. OK- If I get my TA back up with baking soda, then lower my ph with acid, I'm in an endless circle. What steps would you take??

No, you are not. T/A moves with pH but if you add baking soda, it will change the ratio. It will still move but it will be from a higher level.

You need to get your pH into the low 7's if you want to clear your pool. That way the chlorine can do its job.

So add acid correct? Don't worry about TA right now?

I had the same situation 4 months ago. As usual, Carl's advice is 'spot on.'

Keep working on the Ph to get it down. Personally, I target 7.2-7.4. With SWG, it is a constant fight to get Ph down. If I miss two or three days, it can creep back up to 8, no problem. I ususally add acid daily. Just the way it goes for me.

And as you add acid, the TA will go down as well. Use bleachcalc (on this forum or you can google it) to figure out how much baking soda it takes to raise your TA 10 points. then you know how much to add. as a precaution, add the baking soda in two doses over two days, with test inbetween, so you don't overshoot. because of the relationship between lowering Ph and TA, you might want to shoot for 100ppm on your TA so you have 20ppm buffer (down to 80) to work with. Just a suggestion, but works well for me.

It can be frustrating. Stick with it. Eventually you'll get a feel for how much acid you are adding and how often you need to add baking soda. You'll find yourself testing at less-frequent, but safe, intervals that take up less of your time. It does get better pretty quickly.

If you have a costco nearby, they sell baking soda in a 12 lb bag. works out to be about 40 cents a pound. Cheap.

Thanks SoCal-

It's been about 5 days now. Pool is looking better- but bottom drains are still not crystal clear. I'm shooting for TA of 100-110 then acid down Ph. I just measured Ph- hard to tell the reading- It looks like a dark orange- not a dark pink; I'm thinking around 7.3 or so- I still see a little bit of tan colored stuff on the seams of my liner- It poofs very easily, so I don't think it's dirt. Some sort of algae- Cl is still real high- almost orange if I don't dilute it- around 15 I believe. I put in 4 lbs of baking soda and will add aboutaise ppm by 10. I just want my water to clear. I wonder if the brown is mustard algae?? Maybe poly time??

Personally, I wouldn't poly until you've held a chlorine level from sundown to the next morning, and the stuff is still there. Until then, you've got something eating your chlorine. It can take days (took me 6 days with a mustard algae bloom earlier this year). Be patient. Make room in the recycling bin for bleach bottles. Brush twice a day.

Make sure you check your CYA level to make sure you are hitting it with enough chlorine.

Opps, see that you posted your CYA of 40 in the first post. My bad. 15ppm for shock should do it according to Ben's Best Guess Chart. Still wouldn't consider poly until you held constant chlorine level overnight.

SoCAl-
My chlorine has been constant for a couple of days- I even put 2 more gallons of bleach in last night. My last pool store said my CYA was 30. One said 40. Should I try to raise to help out my chlorine?
I hear that mustard alge is resistant to chlorine. I see no color top the water- just no sparkle- kinda hazy. I'm trying to keep my ph low (7.2) to help out. It just seem to be helping. I've got my son's b'day party saturday and want this to be ready. I also smell a lot of bleach- probably due to adding so much.

CYA level is personal preference. Can't really tell you that 30 or 40 is 'bad'. I personally shoot for about 50 in my pool, but that is what seems to work for me.

There are others who have a lot more experience in caring for pools (especially vinyl) than I do, but if you held a constant chlorine level over night, then I think you are good on the shocking, except for (maybe) the existance of whatever it is you seem on your seams. I'd keep brushing and vacuuming.

Poly is certainly an option to consider. Get the 60% stuff if you do.