Cannot maintain FC at recommended levels

[Mike408]

Hello all,

I have taken over care of a 25k in ground plaster pool with in ground spa.

Somewhat recently (before I took over) there was significant algae bloom and when I say significant, you could put your hand in the water and it would disappear.

Using the advice gleaned from reading this forum I have restored the water to being if not crystal clear pretty darn close to it. Partly balancing chemicals, a LOT and I mean a LOT of brushing.

Having reviewed months of water test results from Leslie's (I know this is not highly recommended but it's been the go to for homeowner) the water had been in pretty good shape leading up to the algae bloom but I noticed, very consistently, the FC has never budged above ~0.15 or so.

I have the water very stable with all metrics in good range and have tried to follow the SLAM protocol but as usual, no matter how I super chlorinate it's undetectable a day later.

My cya is about 35, it's not been higher but I believe that number to be accurate.

PH 7.4 alkalinity 85 tds 700 and my total chlorine perfectly matches free chlorine. No problem with calcium hardness or heavy metals.

Two nights ago I went all out and shocked with 3 bags of power powder plus (shock from Leslie's, I believe even two bags is supposed to be enough for this size pool?) and three gallons of liquid chlorine. The water was literally burning my skin slightly.

This morning I checked the FC at home and as usual came up with zero fc or such a small amount it won't register on the dpd test.

Am I missing something or expecting something unrealistic? I keep reading my pool should be able to hold 4-5ppm FC and at most lose 1ppm in a 24 hour period is that accurate? What's the goal here if something other than what I listed?

The SLAM process is kinda vague and does not detail what to do after shock. How do you pros maintain chlorine levels day to day? I am totally unsure what to do from here.

No issues with cloudy water and in fact I can brush the pool and not kick up any cloudy water, it stays perfectly clear after brushing. I feel I am on the right track but darnit why won't the pool hold a measurable amount of FC?

I am a water snob you will not find leaves or debris in the water, ever. I do try to cover my bases


When I add chlorine I detach the pool sweep and run the main pump and booster and pour the chlorine slowly into the return jet taking two minutes per gallon. And after I add chlorine I (never guess never) brush the pool again!

The pool is old and the plaster has been badly eaten away which I assumed was because the calcium hardness was super low for a long time (100-120range with 250 and up being ideal I think) but reading a post here says old plaster can become a chlorine draw is that true? I can attach pics if that helps, the plaster all over the pool has been steadily eaten by something.

Forgot to mention a few years back the pump went out and homeowner gave up and let the pool turn into a pond. The city dumped in mosquito fish and everything. It stayed that way a good three or four years I reckon. We drained it powerwashed the plaster and refilled it. I do recall the plaster looking much better at that time what was about 1.5 years ago now.

 

[Texas Splash]

Welcome to TFP! Everything done so far is what I would call old-school, poo store methodology. The TFP SLAM Process was never technically performed accurately or to the point that all 3 SLAM criteria passed. Water testing did not appear to be accomplished with a TF-100 or Taylor K-2006C test kit, so nothing was accurate.

You must have a TF-100 or Taylor K-2006C test kit. No way around it. Post a full set of those numbers and I have no doubt we can show you how to maintain not just "okay water", but crystal clear to the main drain with no burning, smells, or anything else. But it all starts with he proper test kit. Also be sure to bookmark our Pool Care Basics page for lots of great info.

 

[Oly]

Having reviewed months of water test results from Leslie's.....

This is not helping you at all and is the root of your frustrations.

I have the water very stable with all metrics in good range and have tried to follow the SLAM protocol.....

My cya is about 35, I believe that number to be accurate......

Am I missing something or expecting something unrealistic?

These statements are all underlying assumptions based upon improper water testing. You are flying blind, boldly but blindly.

The SLAM process is kinda vague and does not detail what to do after shock.

The SLAM Process is not vague. If and when you have reached the SLAM level you then maintain until all criteria are met, very clear.
You have never eradicated the organic contaminants and are on a slippery slope, spinning your wheels. Get to the top of the mountain. A proper test kit is required, without this tool, balancing and maintaining your water chemistry is not possible with the TFP method.

 

[jark87]

does not detail what to do after shock.

The key is that there is no “shock”. You get the pool to SLAM level and leave it there, testing multiple times per day and adding chlorine as needed to maintain that SLAM level until you pass all of the SLAM criteria. It’s not a one and done thing and can take several days and you must maintain your FC at the SLAM level the entire time. Hope that helps.

 

[jark87]

And as stated above, you’ll need a good test kit to get through a SLAM. Even if your pool store has accurate testing, unless they’re right next door and open 24/7, you’ll need to do your own testing.

 

[.ben]

Other people have provided great advice but I will add one more point. A normal pool will NOT only lose 1 ppm of chlorine per day in the summer. More realistic is 2-4 ppm per day, or more in extreme heat. My pool goes through almost 5 recently.

You likely have organics (algae) consuming more of your chlorine. A proper SLAM will clear your pool. After SLAM you must maintain proper levels of FC based on your CYA. But everything starts with accurate testing which the pool store simply cannot provide.

 

[Mike408]

Ok thank you for the input all. I will purchase a more reliable dpd test kit as recommended and go from there.

 

[Mike408]

So small update here, I have purchased a tf100 kit which is due to arrive any day. After I made this thread my filter housing sprung a leak and I instantly came to know about bulkhead fittings (never heard of before.) The cartridge filter we have is a c4000 from Hayward, It took some detective work but I managed to find a used fitting on ebay and got my leak taken care of.

But not before getting blasted by water, of course. I made a short term fix with epoxy on what was left of the old fitting and basically just epoxied it to the housing and when my pump was priming WHAMMO it was like standing in front of a fire hydrant haha.

Anyway I gathered materials and have been slamming my pool since about two days ago now. The cheap test kit I have is telling me I have "way more" FC than it's willing to calculate but I estimate I'm nearing 15-18 ppm but that's only a guess based on past testing and reasonable knowledge (all of which I gained by reading this forum) and time being I'm adding 4-5 gallons a day of LC until the tf100 comes in. And I brush, at least 4-5 times a day with a nylon brush from Leslie's and I picked up a soft metal brush yesterday.

So what's interesting is that I may have a much worse algae problem than I thought. I have all this black...stuff around the pool which I thought was from acid washing or something but may be black algae. A lot of it. I was able to brush some off once the FC spiked yesterday before the sun came up, I will attach pictures.

The troublesome thing is that the original plaster color is not white it's like a teal color or something along those lines. Supposed to match the waterline tiles you'll see in the pictures.

Since getting the FC to slam levels I noticed right away this odd color stuff receding all around the pool. Upon closer inspection I think what I'm looking at is black and green algae kind of everywhere in some areas.

Important history about the pool, it's about 30 years old and the owner so far as I can tell NEVER maintained a proper FC level he would add enough chlorine to keep the water kind of clear and acid to keep the pH kind of reasonable but past tests showed the pH always too high upper 8s usually. A few years ago the pump went out and the owner gave up which resulted in an actual pond. The city showed up one day and then we had fish! Yes mosquito fish, for several years the pool had fish and all manor of aquatic life.

We eventually got the pump fixed drained the pool (yuck) and acid washed the plaster refilled and the owner did all the chemicals with Leslie's to guide him. It's been kept that way until I took over pretty recently.

So, show of hands who thinks there is a latent and severe algae problem? I know I know ..

That weird yellow white stuff at the bottom of the spa is growing and showing up in different areas of the pool now. Idk what it is.

Picture 4 bottom left hand corner (of the picture) where the line of tiles begins (two in a row) in that area yesterday there was quite a bit more black stuff I brushed like a madman with a soft nylon brush and got some poofs of stuff a dark green color and most of it vanished but it seems to have left something behind. I don't know how to describe it really, almost like a stain it left behind. An imprint maybe.

Any input appreciated. Thank you all and God Bless..

 

[Mike408]

So nobody has any opinions on the big stains in the pool? I think I've ruled out it being black algae.

The homeowner is really getting on my bad side, he does not want to Invest In a swg and refuses to test the water or add chemicals in any kind of useful educated fashion. It's starting to look like I have wasted my time here. I've kept the FC extremely high while I wait for the tf100 so I can perform the oclt and once I'm done with that I'm turning the pool back over and I'm sure he will just go back to what he always did, add just enough chlorine to keep algae from turning the pool green and keep going to Leslie's for advice. NOTHING I have taught him is sinking in.

This is very frustrating.

 

[Mike408]

So tf100 kit came in today, I followed all instructions and here are the results.



FC=9.5
cc=0
pH= 7.5
ch= 325
TA=120
cya- 40
Tds-1500
Temp-82

Pool losing 3ppm per day FC approx

I suppose I've solved my own problems. Thread closed.

 

[mknauss]

I suspect the stains are metal. Could be copper, could be silver, hard to tell from the pictures. Algaecides.

 

[Mdragger88]

Do an Overnight Chlorine Loss Test to rule out organics left in the water.
The 3 end of slam criteria are :
CC is 0.5 or lower;
You pass an Overnight Chlorine Loss Test
AND
the water is clear.
(Crystal Clear w/no algae dead or alive)

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