Cloudy/Milky Pool. Is My Filter Too Small?

CrystalSun

Silver Supporter
Jul 12, 2017
33
Brooklyn
Hi everyone!

I didn't have a pool till 2 weeks ago but I've been lurking around on this forum for quite some time, I just enjoyed the knowledge. Thank you!

I will try to make it short and to the point.

July 1
I got the pool 6 weeks after it was filled with fresh water but it was GREEN due to not running the filter because of a leak and the water level dropping below the skimmer. I want to use it this summer so instead of fixing the leak now I bought an automatic leveler and turned on the pump and started slamming.

Since it's fresh water the alkalinity and PH were low (source water 20 PPM alkalinity) but I didn't raise it because I've read that when fighting algae it's better to have a low PH. (False?)

After a few days the water turned milky blue but I see very little improvement since. I can see the floor through a haze at the shallow part but it's far from clear.

I'm cleaning my cartridges, vacuumed twice (by pool company) and brushing regularly.

My last 2 test results are below.

Do you think my filter is undersized? If so, what type of filter should I get?

Test results last night

FC 25
CC .8
PH 6.8
Alkalinity 35
CYA 55
CH 80

Today at 1:00PM
FC 24
CC <.5
 

CrystalSun

Silver Supporter
Jul 12, 2017
33
Brooklyn
If anyone can answer these questions I'd be really grateful!

Is my filter too small?
Do I need to bring up my PH and TA levels in order to get the pool clear?
 

RadEngr70

Gold Supporter
May 9, 2017
61
Central, OK
If anyone can answer these questions I'd be really grateful!

Is my filter too small?
I think it's fair to say that it's substantially undersized for a pool your size. I've seen cartridge filter sizing recommendations that put the minimum at 100 SQFT of filtration area per 10,000 gallons. (Some sizing recommendations are MUCH higher than that). You're pool at 35,000 gallons would indicate a minimum filter size of 350 SQFT, yours is 225 SQFT. The real answer is this. Are you having to clean your cartridges more than you want? Are you unhappy with how fast your water clears after a water issue (e.g. Algae Bloom)? Does your water stay murky when the water chemistry is correct? If the answer is 'yes' to these questions, you may want to consider a bigger filter.

CrystalSun said:
Do I need to bring up my PH and TA levels in order to get the pool clear?
Not sure that will have a big affect on clarity, but it could... You need to get your PH up as soon as possible. You're pool water is quite acidic and could be leaching calcium from your pool plaster (grout in your case? is it a tile pool?), which could add to the cloudiness. The TA should be brought up as well, to help insure the PH doesn't continue to strongly trend lower.

Good Luck.
 

CrystalSun

Silver Supporter
Jul 12, 2017
33
Brooklyn
I think it's fair to say that it's substantially undersized for a pool your size. I've seen cartridge filter sizing recommendations that put the minimum at 100 SQFT of filtration area per 10,000 gallons. (Some sizing recommendations are MUCH higher than that). You're pool at 35,000 gallons would indicate a minimum filter size of 350 SQFT, yours is 225 SQFT. The real answer is this. Are you having to clean your cartridges more than you want? Are you unhappy with how fast your water clears after a water issue (e.g. Algae Bloom)? Does your water stay murky when the water chemistry is correct? If the answer is 'yes' to these questions, you may want to consider a bigger filter.



Not sure that will have a big affect on clarity, but it could... You need to get your PH up as soon as possible. You're pool water is quite acidic and could be leaching calcium from your pool plaster (grout in your case? is it a tile pool?), which could add to the cloudiness. The TA should be brought up as well, to help insure the PH doesn't continue to strongly trend lower.

Good Luck.
Thanks man!

My water was only six weeks old and we're up to day 11 of slamming and it's still not clear so I believe that's too long. Am I right?

Yes, it is a tiled pool. Can I work on my TA while FC is that high? I'm afraid that raising the TA will bring up the PH too high but I won't be able to see it since the test results will not be accurate. High PH in this situation will cause more of a problem than low PH. What do you suggest?
 

RadEngr70

Gold Supporter
May 9, 2017
61
Central, OK
I think I'd risk letting my FC fall, to get an accurate PH reading, and then readjust PH, TA, and CH. Your TA is awful low as is your CH. I worry about the effects on your tile grout. (I'd aim for 60 - 80 TA (you can bring it up more later if your PH continues to trend low), get you CH to 300, and PH to 7.2 - 7.4) Then bring your FC back to SLAM levels until your water is clear.
 

Fingaling

Well-known member
Jun 4, 2015
283
Winnipeg, MB, Canada
Hello.

Part of the problem could be you're letting your FC get much too low. With a CYA of 80, shock level is 32.

Have you been maintaining it at that level?

Usually when the pool is that color the algae is mostly dead, but perhaps your not quite high enough FC levels are merely keeping it at bay partially from re-greening.

Low ph let's chlorine work better, but 6.8, and possibly less than that, it's potentially damaging to your equipment and pool.

I wouldn't worry about TA until your pool is clear.
 

LFrankow

LifeTime Supporter
Sep 27, 2012
581
Medicine Hat, Alberta
From the SLAM instructions
Check and adjust the PH to between 7.2 and 7.5. The PH test isn't reliable during SLAMing so make sure to take care of this before you start.
Run the pump 24/7 until you are done SLAMing
How are you doing on the first two criteria, cc and fc loss?
Looks to me like you pretty much have it killed off, just have to be vigilant until it clears.
 

CrystalSun

Silver Supporter
Jul 12, 2017
33
Brooklyn
Thanks for all responses! Amazing website, good people!

I think I'd risk letting my FC fall, to get an accurate PH reading, and then readjust PH, TA, and CH. Your TA is awful low as is your CH. I worry about the effects on your tile grout. (I'd aim for 60 - 80 TA (you can bring it up more later if your PH continues to trend low), get you CH to 300, and PH to 7.2 - 7.4) Then bring your FC back to SLAM levels until your water is clear.
I'm afraid I shouldn't lose everything I gained the past 11 days in terms of slamming.
Hello.

Part of the problem could be you're letting your FC get much too low. With a CYA of 80, shock level is 32.

Have you been maintaining it at that level?

Usually when the pool is that color the algae is mostly dead, but perhaps your not quite high enough FC levels are merely keeping it at bay partially from re-greening.

Low ph let's chlorine work better, but 6.8, and possibly less than that, it's potentially damaging to your equipment and pool.

I wouldn't worry about TA until your pool is clear.
My CYA is at 55-60 so I believe I'm at the right FC level. Are you saying I should raise my PH before the TA?
From the SLAM instructions

How are you doing on the first two criteria, cc and fc loss?
Looks to me like you pretty much have it killed off, just have to be vigilant until it clears.
I couldn't test my PH before starting. The water was DARK GREEN. I thought the color of the test will be affected by the water color. Is that wrong?

CC is fluctuating 1<
OCLT still losing 2-3 PPM
 

Fingaling

Well-known member
Jun 4, 2015
283
Winnipeg, MB, Canada
Thanks for all responses! Amazing website, good people!


I'm afraid I shouldn't lose everything I gained the past 11 days in terms is slamming.

My CYA is at 55-60 so I believe I'm at the right FC level. Are you saying I should raise my PH before the TA?
My CC is fluctuating 1<
OCLT still losing 2-3 PPM
Shoot. Sorry. Must have looked at CH instead of CYA.

Yes. I'd borax that to get it up. Waiting for TA and aeration could take a while and 6.8 or less is very corrosive
 

RadEngr70

Gold Supporter
May 9, 2017
61
Central, OK
I'm afraid I shouldn't lose everything I gained the past 11 days in terms of slamming.
Normally I'd agree with you, but looking at your numbers:

PH: 6.8
TA: 35
CH: 80
CYA: 55
Water Temp: 80F (guess)

Even if we assume that your PH reading isn't accurate because of the high FC levels, and that it's really 7.4. This gives you a CSI that is somewhere in the vicinity of -1.3. Anything lower than -0.6 is considered detrimental to plaster pools, because of the waters tendency to leach calcium out of the plaster. Because you have a tile pool, the only place to leach this calcium is the grout lines... not much of that there to begin with.
 

CrystalSun

Silver Supporter
Jul 12, 2017
33
Brooklyn
Normally I'd agree with you, but looking at your numbers:

PH: 6.8
TA: 35
CH: 80
CYA: 55
Water Temp: 80F (guess)

Even if we assume that your PH reading isn't accurate because of the high FC levels, and that it's really 7.4. This gives you a CSI that is somewhere in the vicinity of -1.3. Anything lower than -0.6 is considered detrimental to plaster pools, because of the waters tendency to leach calcium out of the plaster. Because you have a tile pool, the only place to leach this calcium is the grout lines... not much of that there to begin with.
how about raising just the calcium to get it a little better?
 

CrystalSun

Silver Supporter
Jul 12, 2017
33
Brooklyn
Question,

If my piping doesn't allow flow greater than -let's say- 60 GPM. Would I gain anything from a larger filter (other than longer periods between cartridge cleaning)?
 

jblizzle

Mod Squad
TFP Expert
LifeTime Supporter
May 19, 2010
43,238
Tucson, AZ
There is no real limit on the flow that can go through a pipe. A larger filter would lower one source of headloss and thus increase flow rate.
 

jblizzle

Mod Squad
TFP Expert
LifeTime Supporter
May 19, 2010
43,238
Tucson, AZ
Given your pool size and climate (short season) ... yes you are a little crazy. :mrgreen:

I would think that the 425 would have been plenty, cheaper, and cheaper replacement cartridges when the time comes.