Cloudy Water - Can't Figure It Out

[mculik5]

The water in my pool is cloudy. It's not bad, as I can still see the bottom of the deep end (8'), but it's noticeably cloudy. The water is not green or anything like that, though there are a few spots of algae on the pool walls that have no grown (or gone away) during the past few days of SLAMing.

Here's the rundown:

- Noticed cloudiness and some algae on 7/8.
- Was out of bleach, so started SLAMing on 7/9.
- CYA at the time was ~40, so targeted FC 16.
- Decided to do an OCLT that night for the heck of it. FC 15.5 after the sun went down, and FC 15.5 again the next morning (7/10) before the sun came up.
- Checked the chlorine again after getting home from work. FC 9.5 and the water still didn't look right, so I added more bleach to bring it back up to FC 16.
- Checked the chlorine yesterday morning. FC 16.
- Was busy last night, so I forgot to check the chlorine.
- Checked the chlorine this morning. FC 11. I meant to add enough chlorine to bring it up to FC 20 (because FC 16 doesn't seem to be working, and there is some subjectivity to the CYA test), but forgot before I left for work...

Here are some other details:

- "I've" been vacuuming the pool once per day (Doheny's Discovery).
- I run the pump 24 hours/day. 22 hours on low speed and 2 hours on high speed, which is enough to turn the pool over once per day based on my flow meter.
- All test numbers achieved using the TF-100, a digital pH meter I use for hydroponics, and a TDS meter I also use for hydroponics.

Here are the other test numbers and details, which have been consistent over the course of this issue:

- pH: 7.4-7.6
- CYA: 40-50
- CC: has always been 0.5 or 0
- TA: 110
- CH: 100 (don't usually check this, as the pool is vinyl, but checked this morning)
- Temp: ~80F
- LSI: -0.1, water is balanced (Pool Langelier Saturation Index Calculator | King Technology)
- TDS: 550 (don't usually check this, but checked this morning)
- Physical Debris: almost none (we don't have any trees over the pool or anything; with regard to leaves and stuff, the water is VERY clean)

This is my first season using the BBB method, and it has been working great until now.

Any ideas what could be causing the cloudiness? Also, is the algae on the walls likely dead, and just needs to be scrubbed/vacuumed? Or should dead algae disappear in the pool?

Thanks.

 

[BattleOfYakima]

Cartridge, sand, or de filter? Does it need to be cleaned/backwashed?

Dead algae must be filtered out. Sometimes a slow manual vac is best. Always brush anything off walls/floors.

Algae has a biofilm protective layer that even soft brushing rips and allows chlorine in to sanitize it. Brushing more while FC is 16 might be your key to victory.

 

[Richard320]

Any ideas what could be causing the cloudiness? Also, is the algae on the walls likely dead, and just needs to be scrubbed/vacuumed? Or should dead algae disappear in the pool?

Thanks.

The algae has likely developed a protective biofilm that keeps the chlorine from killing it. Algae needs sunlight to grow, so it stops at night. During the day, it resumes growing and using up the bleach.

You're going to have to break a sweat and brush the pool manually. Also behind lights, inside the skimmer throat, autofill inlet if equipped, beneath or inside the ladder rungs, everywhere. That will expose the algae to the chlorinated water so it can be killed.

 

[mculik5]

Sorry...thought I had updated my signature with that information.

Sand filter. I backwashed it after the 4th of July weekend, and my pressure hasn't increased since then.

Vacuuming and brushing are no problem. For some reason, I thought that stirring the algae up in the water would make it easier for the algae to continue to bloom, so I made a point not bother it on the walls (other than whatever the automatic vac did, which apparently hasn't been much).

I will add more chlorine tonight. Our water level is also a little high right now because of recent rain, so I'll also manually vacuum to waste tonight.

In the meantime, is there anything else that could be causing the cloudiness? If the algae is contained underneath its biofilm on the walls, what is in the water that is causing the cloudiness?

Thanks!

 

[Richard320]

Sorry...thought I had updated my signature with that information.

Sand filter. I backwashed it after the 4th of July weekend, and my pressure hasn't increased since then.

Vacuuming and brushing are no problem. For some reason, I thought that stirring the algae up in the water would make it easier for the algae to continue to bloom, so I made a point not bother it on the walls (other than whatever the automatic vac did, which apparently hasn't been much).

I will add more chlorine tonight. Our water level is also a little high right now because of recent rain, so I'll also manually vacuum to waste tonight.

In the meantime, is there anything else that could be causing the cloudiness? If the algae is contained underneath its biofilm on the walls, what is in the water that is causing the cloudiness?

Thanks!

The stuff you're killing. You're at a stalemate. You kill some and more grows to replace it. The way to clear water is to kill it faster than it can reproduce and ultimately kill it all.

 

[BattleOfYakima]

I've seen many cases where countless tiny grey dead algae particles and super fine pollen resulted in the clouded water and it wasn't until users with undersized sand filters waited weeks or sped up the process via DE/CF/filterglass/whatever through add-de-to-a-sand-filter. Hairnets in the skimmer can also sometimes help. Sometimes it is just too small of a filter for the pool. Sometimes it is less than ideal sand in the filter (not all filter sands are created equal. Sometimes it is just so many particles you need more time or DE to really catch the smallest stuff faster. Sometimes it is that the sand filter needs a Deep-Cleaning-a-Sand-Filter. It is really important to make sure you've gotten all the algae brushed so it is all scratched and has lots of surface area for bleach to attack. If it is on a wall/floor roughly half of it is protected from bleach. You want it all agitated and getting sucked into the filter.

Maintaining shock level is essential as long as there is any live algae remaining. Pull out your plastic ladder and clean it. The bottom rest part too. There are horror stories about those being filled with algae, and some people weren't able to finish a SLAM until they broke it down. There are threads about how to clean them. Richard320 is actually the most legendary of algae hunters on the site in my opinion. He has made threads just about where algae likes to hide and helped countless people find that last spot! If he tells you something about algae, it is good as gold...or platinum really.

 

[mculik5]

Got it! Tremendously helpful, thank you!

I had added some DE to my filter before the July 4th weekend, but it reduced the flow rate of my pump (which reduced the effectiveness of my skimmer and cost more money to turn the pool over once/day), and I didn't notice any difference in the water quality. So, I didn't re-add it after backwashing after the holiday weekend. I will add some tonight.

For what it's worth, the sand in the filter (bought it at a pool store, but don't know if it's good or bad sand) is brand new. I completely removed the old sand, and completely cleaned the filter, before the start of this season.

Will keep you posted on results.

 

[BattleOfYakima]

The amount of sand is also important - did you follow manufacturer suggestion?

You might be adding too much DE for your exact situation if the flow is greatly restricted from the DE alone. Perhaps only try the amount recommended in pool school to achieve the desired PSI increase.

 

[mculik5]

The sticker on the filter says 300 pounds of sand, so that is how much I added.

Regarding DE, I followed the process described, but it took 10 cups (yes, 10) to increase the PSI by 1. My system typically runs at 21 PSI clean, with the pump on high. I was afraid, after adding 10 cups of DE (and reading that it should take 1-2) and letting it stabilize initially at 22 PSI, that it would spike way up overnight after everything truly stabilized. However, when I checked it in the morning, it was still at 22 PSI. Over the next few days, the pressure went up faster than normal, but even after the long weekend with people in the pool, etc., it was only at ~22.5 PSI.

My flow rate wasn't impacted too badly on the high end, from ~48 GPM to ~40 GPM. But on the low end, the flow was cut in half, from ~20 GPM to ~10 GPM. If you do the math, I was pumping ~32K gallons/day before the DE, and ~18K gallons/day after. To pump the same volume after DE required speeding the pump up considerably, which uses a lot more electricity. Because I didn't notice any benefit, and because the low flow rate was impacting the effectiveness of the skimmer, I decided to move away from DE in the filter.

But...I will try some tonight to see if it helps with this algae/cloudy issue.

 

[BattleOfYakima]

Be sure you are backwashing correctly - 2m bw, rinse until clear or 30s, whichever is longer, bw until clear or 30s, rinse until clear or 30s. Turning off before switching, always.

Don't slack on that FC, brushing, and algae hiding spot hunting - filters can only clear a pool of dead algae, not living.

You should only be losing 1-4ppm FC per 24hr day even with tons of brushing. You should be passing OCLT with the brushing too. If either fails, you are still actively battling a live algae bloom and losing the race, as Richard mentioned. You have to be topping off FC often enough and brushing enough to totally win, not just be winning forever. Precise CYA testing allows for precise shock level. Any doubts on CYA testing? Questions?