Should I SLAM?

[Mamafish]

Hello,
I am very new at pool chemistry. And I have an issue, I could use some expert help with.

I finally got my Taylor-2006 test kit. (It is very cool by the way.)

I was going to do my morning therapy and when I rolled the solar cover off the pool I noticed something on the bottom of the pool!
It is gathering on the bottom of the pool along the seams and around the bottom edge of the pool, and on the steps.
We vacuumed the pool and backwashed it. Then topped off with new water. Tested, put appropriate amount of bleach and borax called for.
Ran the filter all night and this morning the pool had the same stuff on the bottom of the pool. Did everything again except backwash.
The pool looked good not cloudy, But.... 4 hrs later I went to test the pool again and that stuff was back on the bottom along the seams etc.
The pool water is clear and I can see the bottom of the pool well. No odor, But... what is that?!
This is an indoor pool not exposed to the elements, no debris.

These are my #s :
PH 7.8
FC 4.4
CYA 35
CC 0.4
TA 100
pool 80 degrees

Can someone tell me what that is in the pool?
And what I need to do to get rid of it? Do I need to Slam?
I have read so much and I am getting confused on what to do.
Please help.
Thank you.

 

[zethacat]

It sounds like you are not very confused at all. You're seeing something growing in your pool and you recognize it is time to slam. Follow the instructions from the web site precisely and you will be fine.

I assume you have gone through pool school? Here are the important articles:

http://www.troublefreepool.com/content/123-abc-of-pool-water-chemistry

http://www.troublefreepool.com/content/131-basic-pool-care-schedule

If you have any specific questions let us know but it sounds like you are just confused about WHY you got something growing. The only explanation for that would be that at some point you let the FC get below 3, which is your minimum based on your CYA of 35. FC of 4.4 is low. Your target is 7 and you should normally strive to keep it at 7. Can you post a picture of what is invading your pool? (just curiosity, and also I've never seen a pool in a garage before)

When testing your water, use the drop test kit. The strips are usually not as reliable/accurate. Just out of curiosity, is the PH in your fill water very low? I see you added borax.

 

[Mamafish]

Thank you zethacat.

Checked again, drop test, PH at 7.8

I am confused on the CYA, one area of pool school says indoor pools at 0-20 (ABC's of pool water chemistry) and another place says (Handy reference)-(Recommended levels) says Vinyl-with bleach CYA should be at 30-50. Am I reading that wrong?
CYA is an important part of all this correct?

I will try and post pictures.

 

[Mamafish]

Do I do the shock? or the mustard algae shock? (pool calculator, blue area , suggested FC Level)

 

[duraleigh]

CYA is at 35 ppm now so leave it there. You have a fairly wide range but no higher than 35 would be best.

What you are likely seeing is dead algae. It "poofs" up and disappears when you brush it but settles right back at the seams and low places in a pool.

SLAM your pool. Follow the SLAM article to a T. Be mindful you have an indoor pool so it will probably go pretty quickly without too much use of chlorine but it is still a process.....not a one-time dose.

Lower your pH per the article before you SLAM and stop (for now) using borax.......that's causing your pH to rise (read "The ABC's of Pool Water Chemistry" up in Pool School) and it's already as high as it should be.

Mustard algae is irrelevant to your situation.

 

[Mamafish]

Thanks duraleigh.

I started the process last night into the wee hrs.
Thanks, Yes I found that info about the pH in the article "SLAM- shock level and maintain" My pH needed to be at 7.2 7.5 before slaming.
And yes, I will not use any more borax (for now).

I don't think I could do this without the help of TFP. To me it is like rocket science.

I'm pretty sure I will be back to the forum at some point. Again, thank you so much for your guidance. You all are rock stars! Or great chemists!

 

[Divin Dave]

Hi mamafish,
sounds like you have things and hand and are doing well.

Hopefully, I will provide just a word or 2 to help clear your confusion about the CYA levels.
First though, keep in mind that CYA is prominent in protecting the FC from the direct UV rays of the sun, and prevent the UV from burning the FC up too fast.

OK. So.... The vast majority of swimming pools are outside, exposed to UV Rays and so the CYA in the recommended levels chart is for those.

Since indoor pools arent directly exposed to the UV, the CYA can be maintained at a lower level. Hence the value of 20 that is mentioned.

Like duraleigh says, your CYA level is fine. No worries!

hope this helps......

Thank you zethacat.

Checked again, drop test, PH at 7.8

I am confused on the CYA, one area of pool school says indoor pools at 0-20 (ABC's of pool water chemistry) and another place says (Handy reference)-(Recommended levels) says Vinyl-with bleach CYA should be at 30-50. Am I reading that wrong?
CYA is an important part of all this correct?

I will try and post pictures.