The Usual "I Have Algae" Problem

[mmcwhorter]

Are we on the right track here: So, I am posting for a friend named Brian in Owings MD....he came over to my house and marveled at the clarity and cleanliness of my pool....the robot vac had just finished. Yes, it was perfect. He lamented about his pool algae problem...in that, he spends all his time brushing and filtering (24 hours/day) and the algae is back every other day. 30,000-gallon pool with cartridge filter. Marcite. After a few quick questions and introducing him to the TFP method....I think I diagnosed his issue. Having been using Trichlor for the last three years as his primary source of FC I assumed he had a very high CYA (this happened to me in my pre-TFT days, so I feel his pain). He brought some pool water over the next day and YES....using my TFT-100 kit we saw CYA was around 110 ppm. I expected higher. His FC was 25.5 ppm, and CC was virtually nil, TA was 60, and CH was 175 ppm. It's not an SWG pool yet (He wants one now ) He had just 2 days earlier had his water "analyzed" by the pool store folks, and they sold him a 32-ounce/$30 bottom of what I think is polyquat algecide. Too funny. I told him to drain 2 feet of water, refill, we'd check for CYA then....if around 80-90 then we'd continue....we'd add baking soda to get the TA up a bit... calcium too....and maybe SLAM (of course with a CYA of 80 that's a lot of chlorine. Maybe let the CYA work it's way down a bit before closing.

Are we headed in the right direction? Anything else to consider?

I think Brian will be a new member soon.

 

[ajw22]

He brought some pool water over the next day and YES....using my TFT-100 kit we saw CYA was around 110 ppm. I expected higher.

For CYA > 90ppm, repeat the test adjusting the procedure as follows:

1. Fill the mixing bottle to the lower mark (15 ml line) with pool water.
2. Continue filling the mixing bottle to the upper mark (30 ml line) with tap water.
3. Shake briefly to mix.
4. Pour off half of the contents of the mixing bottle, so it is again filled to the lower mark (15 ml line).
5. Continue the test normally from adding R-0013, but multiply the final result by two.

If you need to dilute the pool water further then apply these ratios:

Pool water	Tap or distilled water	Multiply result by
1	1	2
1	2	3
1	4	5

Note that when doing a diluted test not only do you multiply the range of the test you multiply the error rate of the test, so results are a ballpark - not an absolute.

See CYA Testing for tips in how to read the test results.

 

[mmcwhorter]

Yes, I had mentioned this CYA dilution method to him, and I still have the sample. I plan to do this, thanks for the reminder.

 

[mmcwhorter]

So, I'm adding to the thread...to post the results thus far:

It took a few days but my friend got his pool drained 3 feet and refilled. It's 11 feet deep and 30,000 gallons...

His new numbers as of last night at 7 PM are:
CYA from 110 to 60 (great)
TA: 60
CH: 150 (makes perfect sense for CH to drop using low CH fill water)
FC 2.0 (was 25.5 a few days ago and I told him don't add any CL because it's useless till we drain/refill)
CC: 0 (yep, it ain't killing no algae)

So, I advised him to add 9 gallons of 10% CL based on the FC/CYA SLAM chart.
SLAM number is 24.
One hour later we measured again.
FC was 25, and CC was about 2.5 (It's finally killing algae). As expected.
So, SLAM has begun.

He also added 8 pounds of Baking Soda to bring TA up (he needs 8 more I think)... to get to 100-120.
He also added about 8 pounds of Calcium Carbonate he had on hand....and he plans on buying more to get the CH up to about 325. He's going to need a lot more... like 30 pounds.

Since he can't measure FC on his own without me and we are shooting in the dark till he gets his own TFT-100 (he's about 20 minutes from my house).......I advised: 3 gallons CL 10% before bedtime last night, 3 gallons CL 10% in the morning (today)....maybe one gallon at lunch, and bring me another sample taken at sundown. He's about 20 minutes drive away. He's got about 20 gallons of liquid CL in stock and ready to go. I can give him my last 8 pounds of Cal Hypo 73 if needed.

He ordered a TFT-100 kit and it might arrive tomorrow, so he can take over from here. I taught him how to make the measurements...

Also, this morning he said: my water looks better this morning for the first time in 2 months..so that's a plus.

I'll have him take a sample and bring it here tonight.....to see if he can pass OCLT next day.

I asked him if the pool store had measured the CYA...gave him a print out? Did he ask them why they recommended 1 $30 quart of Poly Quat? Do they not recognize that the CYA=110 is a big problem??? He just said: "Man, I trusted them. "I just assumed I was doing something wrong"....and there you have the profit motive for the pool industry in a nutshell.

It's nice to be able to help the dude out. He's a TFP convert now.

 

[mknauss]

A couple items.
Read CC - Further Reading
TA did not need to be raised. Now they will need to add acid to lower the TA due to rising pH.

 

[ajw22]

There was no reason to raise a TA of 60. 60 is fine. 100-120 will just cause his pH to rise more rapidly then necessary.

 

[BDY]

What was the pH? Why bring the TA up from 60? I struggle to keep my TA down so as not to put pressure on my pH so I would have kept it at 60.

My 2 c

Otherwise looks great and he’s got a good friend helping him!!!

 

[mmcwhorter]

pH was 7.3, up from 7.2 measured a few days ago.
My friend's pool is not SWG (yet)...I think I saw on the TFT Test Kit instruction sheet ideal TA for a liquid CL pool is 100-120. Was it 60-90 for Salt?

 

[mknauss]

What Are My Ideal Pool Levels?

Use our tool to find ideal chemical levels for any swimming pool. Check TFP recommended levels on pH, free chlorine, cyanuric acid, and more.

www.troublefreepool.com

 

[mmcwhorter]

I saw this new calculator for the CYA/FC chart for SLAM and maintenance. Very well done.

The TA recommendation I gave Brian was late last night (we were both tired) and I was reading from the laminated TFT-100 instructions. See the PDF attached, it clearly says 100-120 for manually chlorinated pools. Maybe they need to update this document. And when I made this recommendation I honestly thought for a second: "Hmmm, this seems a little high", but I ran with it as Gospel. OH well, we can easily fix that.

 

[BDY]

Attachment not opening for some reason

 

[mknauss]

Maybe they need to update this document.

You are correct. To my knowledge, those are no longer included in their kits. They have a QR code linking to TFPC.

 

[mmcwhorter]

I got a complete reagent refill about 9 months ago and it came laminated with it. I just printed out the ideal numbers from the TFT site and will tape them to the inside of my plastic TFT-100 kit box.

Blind obedience if in writing I guess, cause I can't remember EVERYTHING.

Hey BDY: let's try it as a JPG...not PDF. See attached. TFT-100 kit instructions show 100-120 for TA in a manual CL pool.

 

[BDY]

That’s the same as the card in my kit which should be about the same age. I just never really read that sentence I guess and was focused on SWG from the beginning.

 

[mmcwhorter]

me too...funny. When I made the recommendation for him to add Baking Soda...I said "wait a minute, let me double check the card"....cause my Gut said 60-80...but hey: their it was, in wiriting: 100-120. Power of legitimacy.