Persistently cloudy water

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tbenturner

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Apr 29, 2011
6
I have a problem with my pool being cloudy at the beginning of the season. I have owned the pool for 3 years now, and until recently, I thought it was normal for it to take 3 weeks to a month to clear out the cloudiness. My pool has always been green when I open it, so I shock it several times, and the water goes from green to cloudy blue, then it stays there for weeks. That is where I am now. I went to the pool store, and they told me it was because my phos was >1000, and recommended I add borates to my pool. I know the phosphorus is not the problem, but figured it was about time to give borates a shot, what can it hurt. Here are my numbers pre-borate addition:

pH: 7.6
FC: 2.4
CC: 0
CH: 200
TA: 120
CYA: 40
32,000 gallon in ground pool
200lb sand filter
1 hp pump

I know the FC is low, that is the lowest it has been since I opened it. I added chlorine afterwards, but haven't checked it since. Why is it taking so long for my pool to clear? Do I need to shock it more?

Thanks!
Ben
 
Is it just me or does a 200lb sand filter sound small for a 32,000 gallon pool?

Explain what you mean by "I shock it several times". Shocking is a process and you should only have to go through it once at opening. It sounds like to me you have not gone all the way through the shock process and therefore have never really cleared your pool.
 
How often have you backwashed the filter while it is clearing? I have a 250 lb. sand filter on my 12k+ pool. I don't know what the "rule" is for sizing. Just that "bigger is better".
 
The more research I do, the more I realize how much of a pain this is going to be. Apparently I do have an underpowered sand filter. Some of the web sites I looked at marketed my filter as an above ground and small in ground pools, of which mine is neither. An appropriate filter is going to cost me about $650 for the new filter alone. Ouch. What would be the disadvantage of having an underpowered sand filter? Just what I see, longer time to filter? Anything else? I have to backwash every 3 days or so when I brush every day (unless I vacuum, then I have to backwash about three times while I am vacuuming.) Once I get it clean, I only have to backwash about once a week.

Also I haven't shocked as I should. I just dumped in enough bleach to get the FC up to goal and then left it for a few days before checking it again. In reading the pool school, I guess I need to give it more intense attention. I just thought that since it went from green to cloudy blue I had killed everything. Is that not a good indicator?

BTW, JasonLion your android pool calculator app is great, works like a charm. It is a great reference, since I can carry it with me poolside instead of running back and forth to the computer.
 
shock the heck out of it and add some de in the skimmer- just watch your filter pressure. When I do the de thing, I watch it close and then instead of a total backwash, I just bw for about 30 seconds to "bump it" and then reassess.
 
Your pool going from green to cloudy blue is an indicator that you are killing a lot of algae - but it doesn't tell you anything about how much algae is left! If you only kill off 75% of the algae and then let it grow back for a couple days you can easily end up right where you started.

You are on the right track with Pool School. Keep up the study a bit and the pool wont be a mystery any more.

I'm not a sand filter guy - but backwashing every week for a clean pool seems like an awful lot of work. Is that because the PSI increases in that short a period? I would imagine a small filter would run at a much higher psi to a larger one - what is your clean filter PSI normally?
 
lightingguy said:
Your pool going from green to cloudy blue is an indicator that you are killing a lot of algae - but it doesn't tell you anything about how much algae is left! If you only kill off 75% of the algae and then let it grow back for a couple days you can easily end up right where you started.
Click to expand...

It has never gone back to green, so does that mean anything?

lightingguy said:
I'm not a sand filter guy - but backwashing every week for a clean pool seems like an awful lot of work. Is that because the PSI increases in that short a period? I would imagine a small filter would run at a much higher psi to a larger one - what is your clean filter PSI normally?
Click to expand...

My pressure gauge needs to be replaced, but it usually runs at about 12 psi, and I backwash it when it gets to 18-20 psi, sometimes I let it run up to 24. I know it needs to be replaced because when I bought the house it read as above, now it runs at 30 psi when the pump is off, and jumps to 42 when clean. So I just take off 30, accounting for the age of the gauge. It is fairly consistent, but I have a new gauge in the mail.
 
For your filter, you should not exceed 44 gallons per minute. Your 1 HP pump can do more than that. This causes the water to move through the filter too fast and the sand can't hold onto the finer particles.

If you're going to replace the filter, I recommend that you consider getting a DE or cartridge filter, you will be amazed at how clean your water is.
 
JamesW said:
For your filter, you should not exceed 44 gallons per minute. Your 1 HP pump can do more than that. This causes the water to move through the filter too fast and the sand can't hold onto the finer particles.
Click to expand...

According to Hayward, my pump has a rating of 44 gpm. But it looks like that is too small for a pool of my size. The turnover is just over 12 hours, when it should be between 8-10 hours.
 

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lightingguy said:
I'm not a sand filter guy - but backwashing every week for a clean pool seems like an awful lot of work.
Click to expand...

Mine runs 15 clean and I backwash at 23-25. Right now with the robot dead and using only a pool broom and the pool's filter for cleaning, on top of all the pollen and junk we are getting in the pool during the rainy season, I am backwashing about once a month to 6 weeks. It takes about 5 minutes and I'm done.
 
the 200# sand filter should be ok- just takes slightly longer to filter (as noted, 12 hours instead of 8-10...) and have to backflush a little more often- not worth $650 to me to backflush 10 days instead of weekly!
I have a 200# on my 26k gallon pool- slightly smaller, but works great
I do have 2 spd pump, and leave it on low most days- shut down maybe a day a week...
DE and Carts can clean better- but also more pain to clean IMO

Sounds like your cloudy issue you have a handle on- just need to complete the shock process, should go faster than in the past!
 
So I performed the overnight FC test, and I don't think it circulated enough. I put in the bleach at 10:30 last night, waited an hour, and I tested the FC: 20. This morning at 6:30 I tested it and got an FC of 26.5. Yes, I overshot how much bleach to put in, but shouldn't my taylor FAS-DPD kit have given me a good number after an hour? Anyway, there was CC, but it was </= 0.5. It could be less, I didn't want to waste a lot of my reagent knowing that the value was going to be high, so I did the test that was less sensitive (1 drop=0.5 ppm).
 
the CC <.5 is great- not sure why the FC went up...
You don't have a clorinator, or SWCG, or anything, right? (or if you do, they were shut off doing the test?)
Now you just need to maintain shock and filter 24/7 until water clears...
 
tbenturner said:
It has never gone back to green, so does that mean anything?
Click to expand...

Not really. You dont always see green when algae is present and growing. The green just means there is a whole lot of it. Sounds like you are shocking correctly now - so you'll be sorted soon.

RobbieH said:
Mine runs 15 clean and I backwash at 23-25. Right now with the robot dead and using only a pool broom and the pool's filter for cleaning, on top of all the pollen and junk we are getting in the pool during the rainy season, I am backwashing about once a month to 6 weeks. It takes about 5 minutes and I'm done.
Click to expand...

That sounds more realistic. Ultimately it sounds like a larger filter is in order. I wouldn't bother with a larger pump at this time. Even if your 1X turn over rate is a little long - many of us run less than 1 turnover just to conserve power etc. Once the pool is clean and the filter issues are sorted you could experiment with 3/4 turnover or 1/2 turnover and see how the pool holds up. It'll depend on how much debris your pool collects, rain runoff, etc.
 
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