Can't remember all the right numbers

Hi all,

16,000 IG vinyl..we took the cover off a month ago when it warmed up, then it started raining, and raining, and raining. We're in California so the nights are around 40's and the days are hitting mid to high 60's. It's still supposed to rain but we want to get started on whipping the pool back into shape. The pool has grown some algae so we starting heavy duty chlorinating, and pulled out Ben's nifty test kit..here are my numbers.

FC 15
CC .5
TC 15.5
PH 8.2
Alk 170
CYA 28

We don't bother with calcium since we're vinyl. Our plan right now is to keep the FC at 15 for the next few days and shock the heck out of the algae, then get the PH in tune.
I'm not too concerned about the CYA..we've kept the trichlor tablets floating (more or less) all winter and once we get the pool adjusted if it needs more I'll add it. My question is mainly about the Alk..I don't remember what the ideal alkaline reading is for vinyl and how to raise/lower it if need be. Our town is on well water so the alkaline has always been somewhat high. We have the muriatic acid standing by for the PH..but again, want to get the algae taken care of before we go there.
If this isn't the best order let me know..the help from this forum last summer gave us our first year of a beautiful pool and I look forward to another summer of easy care and swimming.

Thanks,

Mary

Quote:

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Originally Posted by maryberrye

Hi all,

16,000 IG vinyl..we took the cover off a month ago when it warmed up, then it started raining, and raining, and raining. We're in California so the nights are around 40's and the days are hitting mid to high 60's. It's still supposed to rain but we want to get started on whipping the pool back into shape. The pool has grown some algae so we starting heavy duty chlorinating, and pulled out Ben's nifty test kit..here are my numbers.

FC 15
CC .5
TC 15.5
PH 8.2
Alk 170
CYA 28

We don't bother with calcium since we're vinyl. Our plan right now is to keep the FC at 15 for the next few days and shock the heck out of the algae, then get the PH in tune.
I'm not too concerned about the CYA..we've kept the trichlor tablets floating (more or less) all winter and once we get the pool adjusted if it needs more I'll add it. My question is mainly about the Alk..I don't remember what the ideal alkaline reading is for vinyl and how to raise/lower it if need be. Our town is on well water so the alkaline has always been somewhat high. We have the muriatic acid standing by for the PH..but again, want to get the algae taken care of before we go there.
If this isn't the best order let me know..the help from this forum last summer gave us our first year of a beautiful pool and I look forward to another summer of easy care and swimming.

Thanks,

Mary

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Mary:
You are worrying about the wrong things. Your ALK at 170 is not a big deal for a vinyl pool. You can go to 200, but I like to think about lowering it when I go past 180, but not 170.

HOWEVER, You MUST get your pH down if you want your chlorine to be effective. At 8.2, you are negating the good of an FC of 15. Add dry acid, or Muriatic Acid to get it down. Your Tri-chlor pucks should help--you can afford to use them (they are VERY low pH) because your CYA is low.

So: Don't worry about T/A--worry about pH. And, by the way, when you get pH down to 7.3-7.8 (I prefer the 7.3 side for fighting algae--give your chlorine every edge you can...) you should find that your T/A measures lower as well. It's not completely independent of pH.

And don't bother with calcium--you are right about that!:D

Thank you Carl :)

We have the PH back in balance at 7.4 and will be putting some algaecide in today to get rid of the creepy crawlies.

Thanks again,

Mary

Don't dump more 'witches brew' junk in the pool!

Need to kill algae in the pool? Use chlorine.

Need to prevent algae in the pool? Use chlorine.

In many/most cases, all you need to do to kill the algae is to raise your FC to the appropriate shock level (based on your CYA, mostly) and KEEP IT THERE until the algae is dead. Then keep it there for another 3 days or so to make sure the algae is dead. Brushing, sweeping, or vacuuming the pool and running the filter and pump to circulate the FC to make sure the FC is able to get to any algae is helpful too.

There are some cases when other 'stuff' can be helpful in getting rid of algae, but usually all you need is time, a little effort, and enough chlorine in the pool.

Thanks for the info Mike. We did try chlorine only. Kept the level at 15/higher for over a week with the pump running 24/7 (it's still on)..swept every day, then vacuumed to waste or ran the Dolphin about every other day. Although it did clear the algae up, it isn't enough to completely remove it, so we are going to the algaecide as a last resort. We only use the polyquat kind to keep gunking to a minimum. As of this morning this is where we stand:

16k gal IG Vinyl
FC 16
CC 0
PH 7.4
Alk 180
CYA 20