Can't get water to clear up.

IceShadow

Gold Supporter
TFP Guide
Jun 8, 2019
2,612
Milwaukee, WI
Pool Size
20000
Surface
Vinyl
Chlorine
Liquid Chlorine
So if I have to replace 75% of the water in the pool, how is doing this method any less expensive then doing a series of draining and filling? I've already drained probably 10-12" out of the pool and replaced the water. I'll continue with this new method tomorrow though.
You can calculate the amount of water exchanged - I have to imagine your pool is at least 3’ deep, but let’s say it’s only 3’ deep. That’s 36”. 5” would be 14% of the pool. That would bring your CYA from 150 to 130. So you do it again - now it’s 112. A third time would take it down to about 96.

If you can afford the water to do it this way, and the patience, great, but it would take 9 exchanges to get it down to under 40 CYA - and that’s if you have a 36” deep pool. Most likely it’s deeper and that number goes way up.

See above. Draining in small steps means the pool water is mixing as you go and that means each drain is subsequently less effective.
 

Edge70

Member
May 16, 2021
15
Belleville Ontario Canada
Pool Size
22700
Surface
Vinyl
Chlorine
Liquid Chlorine
I've got the CYA below 100 now which I know is still pretty high but I think this should continue to come down now as pool water evaporates and we top up with fresh water. I'd like to remove more but it seems so wasteful (and to dump 1/2 the pool water (over 10,000 gallons) to get down to 50 or so...... Maybe this is the wrong approach.

Latest test results show that ph is 7.6, TA is 130, FC is 14 and CYA is about 100. Hard to tell exactly when that dot disappears :) Water is still not clear (see attached photos). Yesterday I did a deep clean of the pool sand filter as per video on site. There was an amazing amount of dirt that came out of the filter but pool still hasn't cleared up since doing this. About 18 hours of solid running now. Pool has been up and running for 2.5 weeks total now since opening by pool company.

So I'm a little confused as to why I can't get the water looking clear? Do you think it's because the CYA is still too high and preventing the chlorine from working properly? The test results don't show anything too out of whack really. One last question, for adding the liquid chlorine, is there a more automated way of doing this or is pouring it in front of a return jet the most common approach?

Thoughts?
 

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IceShadow

Gold Supporter
TFP Guide
Jun 8, 2019
2,612
Milwaukee, WI
Pool Size
20000
Surface
Vinyl
Chlorine
Liquid Chlorine
I've got the CYA below 100 now which I know is still pretty high but I think this should continue to come down now as pool water evaporates and we top up with fresh water. I'd like to remove more but it seems so wasteful (and to dump 1/2 the pool water (over 10,000 gallons) to get down to 50 or so...... Maybe this is the wrong approach.

Latest test results show that ph is 7.6, TA is 130, FC is 14 and CYA is about 100. Hard to tell exactly when that dot disappears :) Water is still not clear (see attached photos). Yesterday I did a deep clean of the pool sand filter as per video on site. There was an amazing amount of dirt that came out of the filter but pool still hasn't cleared up since doing this. About 18 hours of solid running now. Pool has been up and running for 2.5 weeks total now since opening by pool company.

So I'm a little confused as to why I can't get the water looking clear? Do you think it's because the CYA is still too high and preventing the chlorine from working properly? The test results don't show anything too out of whack really. One last question, for adding the liquid chlorine, is there a more automated way of doing this or is pouring it in front of a return jet the most common approach?

Thoughts?
As Donldson said, you won't lose CYA through evaporation -> refill. You will lose some when you lower it via backwashing or pumping out and then fresh water via hose or rain fills it back up. CYA does degrade over time as well but it's very slow, something along the lines of 10ppm a month or so. I would recommend doing a dilluted test - half pool water, half tap water, then test the CYA on that - to ensure you're around 100 (it would show about 50 on that test).

If you wish you can do the SLAM Process with CYA 100. Per the FC/CYA Chart your SLAM level of FC is 39. You'd have to first let your FC drop down below 10 so you can test the pH accurately (most tests for pH don't work when the FC is over 10), then maintain the FC up at 39 by bringing it up there and testing several times a day, adding FC each time to bring it up to 39. This will ensure you don't have any algae you're still fighting to clear up your pool and the filter will take its time doing its job - now that it's deep cleaned it should hopefully be a matter of a few days to another week or so, but you can never tell with sand filters how quickly they will clear it up.

Once the SLAM is done, you'd want to maintain your FC between 11 and 13 until your CYA drops, never letting FC get below 8. You'll have to let it dip down below 10 once in a while to test the pH, then bring it back up to your target range once you adjust the pH.

So your pool is cloudy either because it needs time to filter and the algae is already dead, or because there's still some algae remaining in it that is eating the chlorine and dying but not fast enough to stop it from multiplying more. SLAMming the pool is the best way to rule out #2 and then be sure it filters out as efficiently as possible.

For adding liquid chlorine - you can get automated systems, like a liquid injection pump to put the chlorine in or a saltwater chlorine generator, but otherwise it's adding liquid at the return to let it mix into the pool.
 

Edge70

Member
May 16, 2021
15
Belleville Ontario Canada
Pool Size
22700
Surface
Vinyl
Chlorine
Liquid Chlorine
@IceShadow, good idea on the dilluted test. I will give that a try tonight doing a 50/50 mix to see where I end up. Thanks for the help. Would be nice to get that CYA lower. I did try the replacement method the other night using a 1/3HP sump pump. Says it will pump over 2,000 gallons an hour. I did this for about 4 hours and then shut it down as I didn't want to leave it running all night. I did have to throttle the discharge back a little as my replacement water couldn't keep up. I did this with a slight kink in the hose line. My fresh water is colder than the pool water so I put the sump on the stairs and I added the cold water to the deep end. I may need to do this again by the sounds of it. Does this method sound like I'm doing it correctly?
 

IceShadow

Gold Supporter
TFP Guide
Jun 8, 2019
2,612
Milwaukee, WI
Pool Size
20000
Surface
Vinyl
Chlorine
Liquid Chlorine
Yep, it does! You want to disturb the water as little as possible, so no pump running, hopefully not much waves from the pump, etc.

You can time how fast a 5-gallon bucket fills from your hoses and use that to calculate how long you have to run the replacement, too. A CYA of 30-50 would certainly help you clear things up more quickly by requiring a lower SLAM level, and would help with ongoing maintenance too. It's not great to have to let your FC come down into danger territory just to get a pH reading, and telling your friends they're swimming in 13ppm of FC might freak them out since they won't understand the chemistry the way people who come here do. :)
 

Edge70

Member
May 16, 2021
15
Belleville Ontario Canada
Pool Size
22700
Surface
Vinyl
Chlorine
Liquid Chlorine
@IceShadow, so drain and exchange is underway. My fill hose took 53 seconds to fill a 20L pail so that works out to be about 23L/min, 1358L/hour. Since my pool is a bit over 80,000L, I'm going to do this for 28 hours. I started last night at 7:30pm so this will take me until later this evening - I let it run through the night although I checked on it a few times. I have the fill hose pumping water in the bottom of the deep end and my sump is on the stairs of the shallow end. Seems like a crazy long time but hopefully this will get things back into the right place. Pool pump is off through this process. This has to get me to a lower CYA value. I will have replaced close to 50% of the water in the pool so hopefully I get to a CYA of 50 or so. Then I can do the SLAM process with more manageable numbers! Fingers crossed....
 

IceShadow

Gold Supporter
TFP Guide
Jun 8, 2019
2,612
Milwaukee, WI
Pool Size
20000
Surface
Vinyl
Chlorine
Liquid Chlorine
You should be able to do the CYA test right after the exchange is done (and the pump runs for 30 minutes or so to mix the water). That should let you know where you end up. :) It sounds like a good plan to me!

Keep in mind that some water mixing is going to be inevitable, but it still should knock the CYA down by at least 40% to exchange 50% of the water. If you want to be certain about the CYA dropping by 50% then I would recommend going an extra 5-10% of the water exchange that you're planning.
 
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