Suggestions on causes of cloudy water

[33Mike]

Hi all,

First, thanks to this community. This is my first post, but I've learned a lot reading many of the threads. And now, I will post to ask for some advice. First I'm sure you'll want to know these numbers (all from the Taylor series of test kits):

recently FC: 4-8 ppm range, CC < 0.5 ppm, pH 7.4, TA 70, CYA 40-50 ppm, CH 400 ppm, phosphates 100 ppb

We've had an inground fiberglas pool for about a year. It was built by a fantastic local builder, and I couldn't be happier with it. The builder started me off on the EZ-Pool + cal-hypo tablets for the skimmer. After about 1-2 months of the EZ-Pool program, I elected to stop. EZ-Pool is proprietary and the only thing I knew was in it was copper, which imparted a slight green tint to my daughter's hair. (And most the chemistry labs I spent time in tended to label the contents of containers.) I was able to easily maintain sparkling water with just 1 cal-hypo tablet every 3-4 days and a little dry acid every couple weeks to keep the pH down. I assumed I had no need for EZ-Pool anymore.

Fast forward to this season. For a variety of reasons I elected to open early: mid-March. My strategy for this year was to use liquid chlorine rather than cal-hypo tablets to avoid build up calcium and also allow chemical dosage quickly rather than having to run the pump to get chlorine into the water.

I carefully read the SLAM procedure and followed it, more than once actually. Each time resulted in sparkling clear water and I was able to pass the overnight loss test many nights in a row. I should note that I'm have an opaque safety cover that stays on most the of time. (We have no fence.) So I was "SLAMing" under the cover. Some days after each SLAM the pool water slowly begins to grow cloudy, and then just doesn't clear up. With the cover on FC consumption in a day is less than 1 ppm so I think that suggests there is nothing organic growing there. During the SLAM the entire pool spent over a week with FC well above 10 ppm. I should add that "cloudy" is not milky. I can still see the texture on the fiberglas at the shallow end, but there is a strong halo on the light at night and things like the brush look hazy at the bottom of the deep end.

So, I'm trying to figure out how I went from easy sparkling water last year to fighting haze this year. Here are some things that are different.

1) liquid chlorine (10% sodium hypochlorite "pool shock") instead of cal-hypo tablets and I added CYA -- I was using almost none last year
2) I started running a Dolphin S200 (love it, BTW) instead of vacuuming. For a month my sand filter showed no increase in back pressure (17 psi) and no need to back wash. I thought maybe filter efficiency was the problem with the cloudy water, so I added some DE to the filter this week to get 1 psi raise (18 psi). I also vacuumed with the hose the last two days and this has generated another 2 psi increase (20 psi) today. Maybe the filter will be more efficient now.
3) No EZ-Pool -- surely there was some residual copper in the pool last year that was acting as an algaecide. I have done a few water changes at the 10% level to keep CH levels down, each of those will dilute the copper.
4) I've started experimenting with cycling the pump off and on. Last year I ran the pump 24/7 but it uses as much or more electricity than our entire household. I built a WiFi remote control box this year with time delay relays, etc, to manage the shutdown cycle: heater off first and then pump 5 minutes later after the heat exchanger cools. This has let me easily explore cycling the pump (as well as enabling a number of other conveniences). After I SLAMed and got the water clear, I tried running 50% of the time: 4 hours on and 4 hours off. At the first hint of cloudiness, I started running all the time. And I ran 24/7 during the SLAM. I've been running 24/7 for the last week with still slightly cloudy water.
5) Up to now, lots of time with the cover closed - no sun on the pool. The pool days are spaced with many cool breezy days with lots of tree junk falling from the sky.

Any ideas on the source of the cloudy water?

Also what is typical FC consumption in the sunlight for CYA in the target range? It was a fairly sunny day yesterday and had the pool open all day. It gets direct sun for maybe 6 hours and I think FC loss for the entire day was in the neighborhood of 5 ppm (attempting to account for my addition of chlorine in the afternoon).

Thanks for your help!

Matt

 

[IceShadow]

2-4ppm loss of FC in a day is pretty typical if there are no other issues, just from sun.

Your CH is pretty high. The cloudiness could be from calcium. What is your fill water’s CH / TA / pH? What does Pool Math list as your CSI?

5ppm is also a lot of loss for CYA 50 or so. It could be the start of an algae bloom.

You could try the SLAM Process to see if it clears up, or if your water source is cheap and low on CH, exchange some water to get the CH down and see if that does the trick.

EDIT: Drain/exchange would also help with any copper issues too. Might be a good idea if you can.

 

[pinguy]

Like IceShadow said, I would SLAM again. Cloudiness like you are describing is almost always algea.

 

[33Mike]

Thanks both - Pool Math shows a CSI of about -0.2. My understanding is this pretty far from where one would expect Ca to precipitate. CH has always been high, but I’ve tried to manage the CSI appropriately. When I first started maintaining/testing the pool last year CH was about 800 ppm, and I’ve worked it down with small drain/refill. There were no problems last year with cloudy water and CH well over 400 ppm.

I will try the SLAM again. I’m surprised that there can be any significant algae growth with FC held well over 10 ppm with cover closed (no sunlight at all) for a week. But I agree based on studying these forums that it seems the typical cause of cloudiness is onset of an algae bloom.

Is the use of a flocculant or other off the shelf “clarifiers” recommended? I know most in these forums advocate just chlorine and little else.

Thanks again!

 

[IceShadow]

Flocculants and clarifies are basically glue that bind together the particulate to make it easier for your filter to grab - but they also can gum up your sand. I’d avoid them. You could try deep cleaning your sand filter if you haven’t done it yet. That might help it clear out faster.

 

[Mdragger88]

Have you scrubbed light niche, ladder, other algae hiding places etc? Some people leave the light out during SLAM. Its gotta be hiding somewhere. Slam for 50 cya is 20
How are you testing your water? Just trying to see if we’re missing something.

 

[duraleigh]

How many hours weekly is the pool open to "breathe". It sounds like it is covered more often than not.

 

[33Mike]

At this point in the season the pool is mainly covered. I was able to SLAM and obtain crystal clear water without ever opening the cover. I‘m unsure how the cover affects things. No UV on the pool means no breakdown of CC and gasses can’t escape? But also FC is not broken down and algae growth is not stimulated.. and organic waste doesn’t end up in there. I can try opening the cover more - it is possible since everyone is home now.

There is no ladder. I’ve scrubbed the skimmer. I haven’t removed the light. I’m testing with Taylor K-2006 and the reagents are fresh.

The cover of course is in contact with the entire pool. The underside never sees the light of day, but it is impossible to clean or inspect as it is captured by the tracks on each side. This was also part of my rationale for SLAMing with the cover on, to remove any growth of anything that may be on the underside.

 

[Mdragger88]

I would start slam again & clean the light. The fact that you’re issue keeps reoccurring at regular fc levels indicates you didn’t eradicate algae . Also remember Overnight Chlorine Loss Test is done at slam level fc. During the SLAM Process I would also try to leave the cover off periodically for off gassing. Also Above 10ppm is not the same as 20ppm follow the process exactly. If you’re water is mostly clear it shouldn’t take too long. When you feel you’ve passed all 3 end of slam criteria to be sure u got it you could go to mustard algae levels for 24 hrs Chlorine/CYA Chart
As it likes shade which is something you have
you may also want to deep clean your sand filter if you haven’t here’s a good post with some videos -https://www.troublefreepool.com/threads/deep-cleaning-a-sand-filter.73192/
Afterwards keep fc in target range for your cya which is 6-8 never let it get to the minimum 4.
Best of Luck with this!

 

[duraleigh]

If it was my pool, I would uncover it and SLAM again. I would leave the cover off until I had crystal clear water and had completed the SLAM.

Tehn, I would only cover it about 50% of a 24 hour period. Pools need to "breathe" and will ALWAYS perform better if allowed to do so.

As far as SLAMming with the cover on, that simply is the wrong thing to do. You need UV from the sun to eliminate the CC's that are produced in the presence of high chlorine.

 

[33Mike]

Thanks for the advice. I'll SLAM again. The pool is mostly clear -- photo attached with some junk in the bottom to help judge clarity. I lowered the pH to 7.2 and then added enough liquid chlorine to bring the FC up to 20 ppm. I'll keep the cover open and test in about 4 hours and then try to keep the cover open as much as possible throughout the SLAM.

I understand that UV is both a friend and a foe. During the summer swim season the cover is open a lot more than it has been recently. We live in the woods so there is tons of tree debris falling all the time and also fences are not so practical, so the cover is needed both as a safety barrier during the day while we are gone and it keeps loads of junk out of the pool.

A note to others who may be comparing with their own experience: with the cover on I held about 17-18 ppm FC for 48 hours without any chlorine additions. With every test CC was never over 0.5 ppm. (With the Taylor test kit, CC showed faint pink that vanished with the first drop of reagent.)

What is your advice on filter backwash? As I noted in my original post I was running Dolphin robot with ultra fine media to clean the pool. I went for a month with no change in filter back pressure. It was steady at 17 psi. This past week I added 6 cups of DE to get a 1 psi rise. I then vacuumed twice with the hose and now I'm sitting at 20 psi. The jet pressure at the pool now has a notable reduction. Would you backwash now or keep it like it is with the thought that a partially plugged filter actually filters better?

Thanks again!

 

[IceShadow]

Backwash when the PSI gets to 25% above the base pressure (what it goes back to after a backwash). So if that's 17PSI for you base, backwash is around 21. 20 is probably close enough - your call It's a tradeoff between more filtering power from having some stuff already in it, and having so much blockage that you can't get good flow.

 

[33Mike]

An update: the pool was clearer at the end of the first day of the SLAM. I've been keeping the cover open from early morning until at or after sunset. At the end of day 1: FC = 21.5 ppm and the start of day 2 FC = 19.5 ppm. I raised back to 20 ppm.

On day 2 at 1:00 PM it was 17 ppm, added 42 oz bleach to raise to 20 ppm at 6:30 PM FC was 15 ppm, so I added 70 oz of bleach to raise to 20 ppm. When I closed on day 2 at 8:30 PM FC was 19.5 ppm. That looks like about 8-9 ppm consumption for the day -- it was raining off and on so maybe that added some junk to the pool.

Today is day 3. The day 2-3 FC overnight loss test was 19.5 ppm to 18.5 ppm, with CC = 0.5 ppm in the morning.

The water remains quite clear -- as clear as it has been all season. It would very likely pass the "heads/tails" quarter test in the deep end. I feel like this is where I got to a month ago, so I'm inclined to leave cover open and maintain FC at 20 ppm for another day.

Can I expect to get to the typical 2-4 ppm loss per day that IceShadow noted at FC levels of 20 ppm? Or is the typical loss a fraction of some excess FC so having more means one will lose more?

Thanks again for the advice!

 

[Mdragger88]

Did you check your light niches?

 

[IceShadow]

You would expect to lose more than 2-4ppm FC to the sun at SLAM levels. The more FC, the more UV loss. 2-4 FC is at maintenance levels.

 

[JW1]

Mike - how is the daily FC loss?

 

[33Mike]

After the SLAM, I tried to keep FC around 8 ppm for a week with the cover open all day most days. When the pool was open, I was adding 70-90 oz of 10% which is an FC loss around 6 ppm a day. Water kept clear. One day FC dropped to 2 ppm during peak afternoon sun and the pool started to get a bit cloudy again. I raised to SLAM level and was clear again within 24 hours.

FC loss appears higher than what others noted. It was in bright sun. I also wonder how much it depends on other factors. At 8 ppm the loss is probably greater than at 4 ppm.

The literature (Redirecting) suggests some dependence on pH, but probably small over the ranges we work with. It appears both HOCl and OCl- breakdown with UV.

I’ll keep tinkering with it. I need to order more reagent and retest CYA to be sure I know my level. The black dot test is a little tricky - I’ve read advice on here for how to do it. I may prepare a reference sample with known CYA so I can be sure I’m doing it correctly.

Thanks again for all the help.

 

[JW1]

I’m here in Southwest Ohio, so we have exactly the same climate. My FB pool was installed last October, so this is my first summer. When I leave my solar cover off all day long I’ve been losing more than 2-4 FC. So I went searching the forums and found your thread. I’m having some similar issues. I started today at 8 ppm at 5:45 am. It has dropped to 6.5 ppm at 10:45 am. My CYA is 40, so my range is 3-7. I’ll be testing throughout the day with the solar cover off to see what happens.

 

[33Mike]

Cool - let me know and we can compare notes.

I had no trouble with the overnight loss test at SLAM levels, so I’m fairly sure I eliminated organics prior to observing those losses. Bather load wasn’t too heavy either.

My goal is to get to a point where I can reduce the run time of my pump and maintain sparkling water. I think to do that I’ve got to be sure I understand the difference between slight cloudiness that emerges as a lack of mechanical filtration vs. cloudiness that is the beginning of algae growth due to a lack of FC.

 

[JW1]

I lost 6.5 of FC today. Pool is full sun and was uncovered from 6:30 am to 7:30 pm. UV index got up to nine and had no swimmers today. I fought some cloudiness mid week so I will continue to monitor. Certainly not getting 2-4 FC daily loss right now.