Algae Question about CYA and any other advice?

Hello, I have been studying the website and forums for about a week. I have very dark green algae and cannot see the bottom of the pool. I also have lots of white scale. In the beginning I used a lot of algae treatment, shock and First Aid from the pool store. I have been brushing and vacuuming daily. It will clear some and then go back again. Then I discovered your website and made a trip to Walmart and the pool store yesterday.

My pool is a fiberglass Roman style pool with a built on tiled fountain. 15,000 gallons, installed in 2005. It runs a Hayward 1.5 hp 24" sand filter pump. The pump is filled with DE. We have had an Aqua Logic AQL-P4 salt system with a T-CELL-15. We have had constant problems with the Aqua Logic failing and I have been able to fix it. This time it is beyond repair and the cell is worn out. I have ordered a replacement cell. After putting that in, I should be able to verify if the board is bad again. If so I plan to replace the board. I didn't know the system had failed until the pool turned green. So currently we are running it as a regular chlorinated pool.

I am using test strips to measure. I have bought the test kit from Amazon through the link on your site. It is supposed to be here tomorrow.

Last night my readings were:
TH 500, TC 0, FC 0, pH 8.4, TA 120, CYA 15. I added 311 oz bleach, 35 oz muradic acid, and polyquat algecide.

This morning my readings are TH 250, TC 5, FC 10, pH 7.2, TA 80, CYA 0. I added 5 1/4 cup Borax.

I'm finding some confusing info and have a question. The pool calculator says to add baking soda and CYA. On the pool start up problems page in poolsolutions.com it says to not add any stablizer until the pool is clear and can hold 2 ppm residual chlorine overnight. In some other places it says to not let your stabilizer go below 30.

Should I add CYA? Do I need to add baking soda along with the Borax as the calculator suggests?

What level CYA should I maintain while getting rid of the algae?

Thank you,
Michael

Fiberglass, 15k gallons
Hayward 1.5 hp 24” sand filter refilled with DE

Hi, Michael, and welcome to the Pool Forum! Good for you for doing your homework and reading on the forum and on PoolSolutions!

Since your kit is supposed to arrive tomorrow, just wait and test then and post some good numbers for us to look at. We don't put much trust in test strips. We also don't really like that pool calculator too much.

For now, go ahead and add 3 gallons of plain, unscented 6% bleach (generic is fine) this evening. That should take your chlorine level up to about 12ppm. Don't worry about your pH and alk for now, and let's wait til tomorrow to get an accurate CYA level. If you truly do not have any CYA or very low, you have a couple of choices. You can either buy some and add it separately or you can use some dichlor for awhile which will add chlorine and CYA at the same time. Then, once your CYA level is around 50, you can switch to just bleach. Your choice. Let us know how you want to proceed and post some good numbers tomorrow for us to look at.

Hope this will be enough to help until tomorrow. Then, with some good numbers, someone here can tweak the advice a little more for you.

Definitely, do NOT worry about adding baking soda, for now.

• Only add borax for now, if you need to raise your pH.
• Turn off your SWCG for now.
• Keep your pH on the low end of things.
• Add chlorine (bleach) late in the day; I'd recommend 5 gallon doses (2 more than WaterMom said)
• Brush the pool AFTER adding chlorine.
• Test the pool early the next AM for pH and chlorine; let us know what you find.
• If you have a 2 speed pump, run on low speed 24/7
• Ignore recommendations from the PoolCalculator -- it's very good for some things, but not this.
• Complete the pool chart form, so we have your pool info in one spot -- it takes about 30 seconds, but will save much more than that.

  Pool Chart Entry Form
  Pool Chart Results

Hello again!

I'm sorry if this posted 2x. I wasn't sure it went through and don't know if I'm still moderated and wouldn't see it yet.

Last night I added 3 gallons bleach (that's all I had). I received the test kit this afternoon. My readings are:
FC 22
pH 7.4
CC 1.5
TA 150
CH 210
CYA 84
Sat index 0.06
water temp 85

After looking up my pool contract, I have 8400 gallons. I appreciate any advice you have.

Thank you,
Michael

Fiberglass, 8400 gallons
Hayward 1.5 hp 24” sand filter refilled with DE

Hello again,

Today my FC is 17, ph 7.6, CYA 68 and CC 1. Any advice is appreciated.

Thank you,
Michael

Fiberglass, 8400 gallons
Hayward 1.5 hp 24” sand filter refilled with DE

How does the water look? Test the chlorine within 2 hours of sunrise in the morning and see how much chlorine you lose overnight and also see if you still have a CC reading.

That's an awful big pump for your pool! Sometimes that makes it harder to get an algae bloom cleaned up.

Please add to your signature the fact that you have an SWCG.

Hello,

Yesterday's readings were FC 9, ph 7.6, cya 54, CC 1.5. I added 182 oz bleach last night.

This afternoon the readings are: FC 17, pH 8, CYA 28, CC 0. It looks a bit clearer and the green is definitely lighter. When I brush a lot of algae comes up.

How much CYA should I add. What level FC am I trying to maintain?

Also, my replacement salt cell arrived today. I won't know if the main board is busted until I run the new cell. Should I start up the salt system or wait until things are better?

Thank you,
Michael

Fiberglass, 8400 gallons
Hayward 1.5 hp 24” sand filter refilled with DE, hoping to get my salt system running again

Don't add CYA yet until you get your pool cleared up.

Did you test your pH when the chlorine level was at 17ppm? If so, then your pH reading is probably inaccurate. Testing it at high CL levels usually gives falsely high pH readings. Retest it when the chlorine is lower.

Did you do the overnight test? That is an important test to do and to report here. Chlorine loss during the day may be to sunlight, but chlorine loss overnight means you are fighting something in the water.

Add bleach this evening after the sun is off the pool -- enough to get the chlorine level back up to around 12-15. An hour after adding it, test the chlorine. Then, test it again within two hours of sunrise in the morning. Then, report back here. Be sure you also test and report the CC reading in the morning.

Do not use your SWCG right now. Wait until this is cleared up.