Very green lagoon style pool - helping friend learn TFPC and getting control of pool

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steveg_nh

steveg_nh

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Oct 7, 2013
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Southern NH
Hi All,

I'm converting another friend to the TFPC method. They went away a few weeks ago, and while away, their pump broke. They came home to a mess. The pool store has been trying to "help" to the tune of hundreds of dollars of chemicals, with little to no progress. At one point they had it back to a shady/cloudy greenish blue, but never clear. My guess is chlorine wasn't high enough for long enough (SLAM process) and the algae took over again. Well, my wife offered my services. :) Kind of getting to be known as a Pool Whisperer around town. Fine with me. I enjoy it and enjoy helping people that appreciate it and are willing to learn.

Anyway, I thought I'd start a thread to keep track of the progress and in case I have questions. I actually do have one, about how to do the spa and pool at the same time, but I'll get to that.

First, here's the pool on Day 1, yesterday, 9/7/15 at about 3pm.

day 1.jpg

This is a lagoon style pool with spa. Spa doesn't spill over except for overflow. I'm estimating the pool size at 28,000 gallons. It's gunite. about 40 feet long and averaging 15-17 feet wide. 7 foot deep end, 3 foot shallow end. Spa is around 400 gallons.

Readings that mattered yesterday:

FC: 0 (I stopped there)
CC: 1.5
pH: 9+ (YIKES!)
CYA: 0 (thank goodness)

They had 5 gallon jugs of chlorine from pool store, but I couldn't figure out concentration. I assumed about 12%, but it must have been more. I put in 5 gallons, and 3 hrs later, FC was at 25! I checked again this morning, and it was down to about 19. No sunlight, so obviously we are killing junk in the pool. Nice! I have checked the charts and SLAM should be 10, so I'm going to hold it at at least 12...I will check again tonight around 5pm,. maybe a bit later. And given the high pH, before I treated with chlorine (since I know you can't test pH with pH over 10), I added muriatic acid yesterday to bring pH back down to around 7.4 before I added the chlorine (did it about 1 hr before I added chlorine). They've bought about 10 gallons of bleach so far, and will buy more today.

They are brushing religiously which is great, and have spare cartridges for their filter, so the frequent cleaning of the filter only results in a few minutes of downtime as they swaps filters. Pump for filter is set to maintenance mode so it's runs 24x7 while we fix this.

Here's the question on the spa. The pool and spa share the same filter/pump. There are valves controlling which gets filtered. So when spa is filtering (program is 1 hr per day), the pool is not. When the pool is filtering, the spa is not. The spa, if you drain it, drains into the pool. So I can't run the spa and the pool 24x7 at the same time. I certainly don't want to get the pool clean, and then drain the spa into the pool and put that algae in there. So should I just empty the spa, and refill (only 400 gallons), or just slam it as normal, only running filter about 1 hr per day and stirring it up manually once and a while? Thoughts are appreciated.

Thanks!
 
Wow, not the greatest of choices there huh? To drain or not to drain, that is the (spa) question. If it were me, I would simply drain the spa. Get that junk out of there so the SLAM can focus on the pool and keep that filter going 24/7. Once the spa is emptied, you can give it a thorough manual scrubbing to get it well again. Perhaps purge it (plumbing lines) after cleaning to get any residue out of the lines. Just when you think the pool is back to 100%, go ahead and cycle them both on/off like normal. Hopefully you won't have too much residual junk come back to the pool from the spa by that point. That would be my personal approach. Others may have a different view. We'll see. :)
 
Very green lagoon style pool - helping friend learn TFPC and getting control ...

Some good thoughts. Thanks.

On the pH I didn't check again. Probably should have. Looking at the coloring it didn't seem too much darker than 8.5. In hindsight I should have.

On draining the spa, with it being gunite, are there any concerns with it sitting empty like you would have with a vinyl liner pool? I'm guessing 4-8 days max it would be empty.
 
Is there any chance that they had been maintaining their pool this whole time at 0 cya? I'd say not; most people are either tabs or shock. Which would mean to me, if the CYA disappeared, that you may have a very high initial fight with CL loss.
 
It's a good question, but the answer is I'm not sure. They weren't sure what CYA even was. He said he would manually dose with liquid chlorine and use tabs to compensate. I thought I'd find really high CYA, not 0. Chlorine loss over night was about 5-6ppm. Can you explain a bit more about higher chlorine usage with 0 CYA? Is it the possibility of ammonia?
 
well if they were mostly liquid but only used tabs on occasion, they could have been near 0 anyway. CYA will drop a bit over time. If they were all tabs all the time, then suddenly they are down to 0, then yes there could be concern of ammonia or something. but overnight loss of 5-6 is much less than has been reported in ammonia cases. So you're probably alright.

If you continue to SLAM without any CYA in the pool, you are going to lose a lot to the sun during the day, on top of what you're losing to oxidation. 30 is the recommended level. Even 20 would be worlds of help.
 

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Steve, by using the CYA chart, I would use a CYA target of 30, which would then require an FC SLAM/Shock level of 12. You can start getting the stabilizer in there now and treat accordingly. Maintaining the FC of 12 should work just fine as long as the CYA is programmed to be no higher than 30.
 
Oh ok, that makes MUCH more sense. CYA of 20, yes that's the plan. :) Didn't read it right.

And Texas, I was working towards a FC of 12 for the SLAM. So even though I'm slamming, I'll go ahead and add stabilizer at the same time. One 4 pound canister should bring it to 20 according to Pool Math (assuming my pool volume estimate is correct).

Anyone know what bulk sodium hypochlorite usually is from the pool store, in the 5 gallon jugs? 11.25%? 15?
 
Yes, you can add the stabilizer in there now and let it start working. If it's granular, it takes about a week to register on tests. If it's liquid (more expensive), it should register in about 24 hours. FC of 12 looks good. I've heard of sodium hypochlorite in bulk sold in different concentrations. My local pool store didn't have 5-gal jugs, only the 4 bottles per box (4 gal). Those "used" to be 12%, no they're 10%. :( Some hardware stores have larger supplies though.
 
Thanks. I'll add the stabilizer. I hang the granules in front of the return in an old sock and squeeze it. As soon as I add, I'll SLAM as if I'm at that CYA level (the target of 20).

They called the pool store too. They said it is 15% but because it sits, it's likely lost some strength, so they advertise it as 12%. Given that adding 5 gallons brought the pool from 0 to 26 yesterday, I'm estimating the pool at 23,000 gallons. Man I love pool math!
 
Be sure to take pictures! Especially of a feature that extends into the water. Something like steps, or a ladder. Take the same picture each day and then post them. That way we can all enjoy the transformation.

Plus sometimes a SLAM will appear to stall but if you look at a picture you can see the subtle change that is happening.
 
Very green lagoon style pool - helping friend learn TFPC and getting control ...

Here's day 2. FC was 13 just now (down from 22 this morning!) Going back in a bit to add stabilizer and a bit more chlorine. Looks like a lighter green!

6349ecffcba83540917ae01478295643.jpg
 

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