SLAM not working, chlorine consumption steady (not dropping)

[vandal968]

2nd season with a pool, having some some trouble again. Last year, I got a house with a pool, and non-working DE filter (collapsed grates). Fixed the filter, came to TFP SLAMed it and all went well. It took me a couple of tries to figure out how often I had to cycle the pumps. The answer was twice a day, since it's an infinity pool and the overflows would always deplete chlorine first and go green. After it got away from me a couple of times, I figured out a schedule and a dosage and things settled for the whole season.

Although I ran the filter daily, I got behind on my chlorine over the winter and eventually it got down to nothing. The pool still didn't go green because it was cold. The water is clear, and I'm going through the slam procedure, but the chlorine consumption won't decline, I need to keep adding about a gallon a day. Last year my CYA was 70 and I slammed around 20, this year CYA is 35 (per TF100 and LPS) and I'm trying to SLAM around 14 but I'm not seeing that slow steady decrease in chlorine consumption. Should I just use the very high chlorine levels that I used successfully last time? Could my lower CYA be allowing the chlorine to deplete so much more quickly? Temps are still cool, pool is 72.

thanks,
c

 

[madwil]

Treat the cya as 40, rounding up. Use 16 for your fc. Add as often as you can to keep fc at 16, or even slightly higher. Run filters continuously. And patience

 

[triptyx]

In addition to raising your SLAM level, brush the entire pool (including the infinity wells) as many times a day as you can, and also, check everywhere for algae. Behind the light fixtures, inside the skimmer (under the lid, under the basket, under the diverter valve too if you have one), inside any ladders or rails, on/in anything floating in the pool, etc. Usually this problem is a result of a hidden stash of algae somewhere in the pool.

 

[Analogbytes]

And just to throw it out there, since the chlorine is being consumed, the SLAM is working. Play hide-and-go-seek with the algae. Every SLAM is different, even in the same pool. Hang in there and you will get it.

 

[vandal968]

It's been a over a week now filter running 24x7. Keep adding chlorine to keep my level at 20 for last few days (was 14). Pool is still clear and spotless, chlorine consumption has still not declined at all. Last year I turned it into a green swamp 3x accidentally. In each case I got it under control in about 4 days. It's taking a gallon or more a day with no slowing at all. I've already spent about $100 on bleach and pool has only been open a couple of weeks. What is happening?! C

 

[domct203]

I know this is a hard pill to swallow, but you need some POP (pool owner patience). You are dealing with biological organisms, every SLAM will be different.

Has anything other than chlorine been added to the pool?

A large jug (96oz) of 8.25% bleach adds 6.7ppm to FC in your pool, so I'm guessing you are losing about 5-7ppm a day? How often are you able to test and dose?

 

[vandal968]

I'm now more than 2weeks into the slam, definitely over $100 worth of chlorine, can't imagine what my electric bill is going to be running 2 pumps 24x7 for weeks (infinity pool) and still ZERO change in chlorine consumption (I'm putting in 242 oz daily ($6), when it was stable last summer at a much higher temp it needed 16 oz/daily). Pool is still clear as it's always been but consumption has not declined one iota. This is VERY different from the SLAM results I got last year while following the same procedure on a totally green slimy pool. SLAM was completed in 4-5 days. I know everyone just says to wait and be cool, but is there some point where other tips will be offered? Is there some other aspect of my pool chemistry that could be rendering the chlorine inert? Like once I've spent $1000 on chlorine and electricity, is someone going to say "BTW, you should check...." Because I'd love to hear it now.

cheers,
c

 

[triptyx]

Check inside the skimmer, unscrew the retaining screw for the light fixture and check behind that. Look carefully in the retaining pool. If you have anything at all that is floating or removable in the pool check on/inside it.

Something is in there if you're getting chlorine consumption overnight - somewhere.

 

[Analogbytes]

just to make sure the tests and chlorine are all good, have you tested FC after dosing as well to make sure it rises to what you expect?

 

[jblizzle]

What have your FC and CC test results been? How often you testing and dosing? What does the water look like? Have you tried the OCLT?

 

[krazykrames]

^^^ Have you tried the OCLT? How did your CYA go from 70 to 35???

 

[vandal968]

Sorry I dropped off this thread, I was sick as a dog for two weeks. My chlorine consumption never declined, so I decided to open up my filter and do a cleaning. I found a thin black layer of what I believe was mold or something. It was between a layer of brown silt and the white DE. I used a bondo spreader to gently scrape all the crud off my grids and into a trash bag, then hosed off the grids. The manifold at the top had black staining that didn't want to come off, so I soaked it in 100% bleach for 15 mins until it turned white. Reassembled, recharged, and in a few hours my chlorine level went up. Well, I should explain, in addition to the 1 gallon of bleach the pool was eating per day, I had also put a couple of pucks in the floating thing to help keep my chlorine levels up. In a couple of hours with just the pucks and no added bleach my chlorine level increased from 4 to 6.5 Previously, it kept dropping continuously and drastically. So, it looks like you can have a black mold infestation in the filter itself. Go figure.

Thanks for the help.

c