How long does a typical SLAM take?

[mcmoyer]

Hi all,

I haven't been on the forums in a while. I used to do the TFP method on my above ground pool, but then my wife talked me into getting an inground pool installed. I insisted that we get whatever equipment would make it maintenance free for me...or at least as close as can be.

So now I have a 22k gal pool. It's got a chlorine puck feeder, mineral cartridge and UV filter. It's got a large cartridge filter attached to it as well. It was pretty much maintenance free until this spring, the third year of ownership. Last fall, I noticed that even though it didn't seem like I was using that many pucks, my CYA had gone up to 120. I drained and refilled enough that I got it down to 50ppm. I then swore I would no longer use pucks unless it was an emergency.

I kept that promise over the winter and spring. At the same time we bought a solar blanket and started using it. It was amazing how well that worked. We swam in 80F water on April 19th and have been using the pool almost daily since. During the time the solar blanket was on, I did notice little spots of green algae popping up. I also noticed a bit more chlorine consumption than before, but nothing was ringing alarm bells since the water was very clear.

I started reading a site that talked about not needing much chlorine at all if you had a mineral cartridge and UV filter . It said you could just shock it weekly with bleach or cal-hypo and then between that and the mineral cartridge and UV filter, your water should remain clean. So I decided to try that. So I shocked my pool that first night with some 73% cal hypo and then tested the water then next morning and was surprised at how many ppm it had gone down. I think my initial ppm was 13 and by the next morning it was down to 7ppm. I also started noticing a 1ppm concentration of CC.

I got back on the forums and decided I needed to do a SLAM, but I'm a bit confused by it. My water looks really good. It tests fine for everything else, although Leslie's says that my phosphates are high..but surprisingly they didn't try to sell me the Phosphate free stuff.

I'm only on my 2nd day of the SLAM, but I've already gone through 9 gallons of 12.5%. I'm dipping into my cal-hypo and luckily my CH is a bit low right now at 175 so I think I should be able to continue to use cal-hypo to SLAM. Last night the OCLT went from 24 - 20ppm. During the day with the direct sun, I feel like I'm just constantly adding chlorine. Is there something else I should be looking at? I feel like there's something I'm missing. I just cleaned my filter cartridges in February. The gauge doesn't show any blockage. The water is really clear. Currently there's no green showing as far as I can see.

Here's the last test I did at Leslie's before I started the SLAM

FC - 0.14
TC - 0.14
pH - 7.9 --- I lowered this to 7.2 before I started
TA - 98
CH - 172
CYA - 51
Iron - 0.1
Copper - 0.1
Phosphates - 1735
TDS - 600

So I kind of feel silly for thinking this pool would be maintenance free, or close to it. I obviously let something go wildly out of control. I also wasn't as stringent at testing that I should have been. I was fooled by that clear water. I think that UV filter is what's fooling me. I think it does a decent job of sanitizing water that flows past it. It just can't sanitize the water that never gets to it.

 

[mknauss]

Can you post test results from your own test kit? We do not provide guidance based on pool store tests.

You need to remove the mineral cartridge. It is adding metals to your pool water and will eventually stain it.
The UV does nothing for the bulk pool water. It can be unplugged.

 

[splashpad]

Welcome back!

Liquid Chlorine and a proper test kit, can you fill in your pool & equipment details in your signature please? Thanks!

And yes, you'll be directed to the SLAM Process but you already know that!

 

[Richard320]

You know that UV destroys chlorine, right? So if you're running the UV system you're just cancelling out the chlorine you added. UV can kill viruses and algae, but it only kills the ones inside the chamber. There's no residual in the pool like there is with chlorine. You had too low chlorine for too long and that's why you got algae.

 

[mguzzy]

I haven't been on the forums in a while. I used to do the TFP method on my above ground pool, but then my wife talked me into getting an inground pool installed. I insisted that we get whatever equipment would make it maintenance free for me...or at least as close as can be.

That was your chance to get a SWG.. ... but you can install that later.

 

[mcmoyer]

That was your chance to get a SWG.. ... but you can install that later.

I had messed around with salt water when I had my above ground pool. I got tired of having to clean the plates and then replace them repeatedly. Before we replaced it, I had moved back to an all chlorine pool. We stone work around the inground pool and didn't want to mess with cleaning the salt off of that either.

 

[mcmoyer]

A quick update, my SLAM ended up taking 3 days. My OCLT on the last night was around 0.5ppm. That was from 11pm to 8am. My UV light is hardwired into the system and doesn't have a separate on/off switch. The only thing that controls it is a flow switch. But I guess my OCLT results show it doesn't have much affect. Who knows, maybe the bulbs are EOL'd.

When I posted the test results from Leslie's, that was the first time in 2 years that I had them run a test. They'd even dropped me from their system Mainly I went there to get a good reading on my CYA. I have no idea who to get a good reading on that at home. I've gone through the entire CYA test contents of the TF-100 and still feel like I can't get a good, repeatable reading.

 

[mguzzy]

Mainly I went there to get a good reading on my CYA. I have no idea who to get a good reading on that at home. I've gone through the entire CYA test contents of the TF-100 and still feel like I can't get a good, repeatable reading.

@mknauss had a good way of describing it.. I don't remember where that post was. Fill the tube to each graduation: 100, 90, 80... etc and then look in there. Can you see the dot yes-no, then go to the next one. There is no point in filling the tube to find the exact point at which the spot disappears.. The test is only accurate to increments of 10. and you only need to glance.. otherwise you start to see the dot as a optical illusion formed by the circumference of the tube.

I had messed around with salt water when I had my above ground pool. I got tired of having to clean the plates and then replace them repeatedly. Before we replaced it, I had moved back to an all chlorine pool. We stone work around the inground pool and didn't want to mess with cleaning the salt off of that either.

The SWG tech for in ground pools is pretty solid these days. They are really self cleaning for the most part and if you have to manually clean it its because something else is off in the pool's chemistry to cause the deposits. If you were seeing salt deposits your salinity was WAY to high. I retrofitted my pool with an SWG 15 years ago and took out an old UV system that was defunct. It was the best thing I ever did in the way of a homeowners improvement. I don't know what kind of stone work you have but most of them are not going to react to a salinity that is less that half of your tears. I suggest you reconsider it.

 

[mknauss]

When you do the CYA test, try this next time.

Once you have your solution ready, back to the sun, etc. Fill the vial to a line, say 80, lower the vial to your waist level and glance for the dot, you see it, add solution to the 70 line, glance, see it, repeat until you no longer see it with a glance. Then use the CYA value one step above the line you read. So if you stopped at 50, use 60 ppm CYA.

The vial is in logarithmic scale. So it is not viable to interpolate between the lines. Just use the whole numbers, such as 50, 40, 30, ....