At my wit's end - cloudy water

[chem geek]

His pool is 17,000 gallons, not some sort of small Intex or pop-up pool. A full drain and refill is not necessary nor the least expensive approach. The water isn't even a swamp of a neglected pool. Clearing cloudy water is not rocket science, but as you point out does require a decent filter. Sand can be improved by adding some DE to it. If the particles are a suspension (as opposed to dead algae), then a clarifier can help, but usually is not necessary.

[drain and refill]

If he has already dropped in 35 gallons chlorine and has been running his filter for 2 weeks 4/7 than replacing the water would have been cheaper and faster as its only 17,000gal.
The sand filter is probably on the small side and catching next to nothing. Know im not disagreeing with you it should cleanup if there was a better filter but theres not at this point and it shows just chemicals in water can not fix the problem.

[chem geek]

I agree that he should have tried adding DE to the sand filter a lot earlier and not doing so that water replacement might have been less expensive (depending on water rates where he lives). Trying to clear a pool that has poor circulation and poor filtration won't happen quickly enough using chlorine alone. Also, I now see that in this post he described it as a frog pond prior to this cleanup, so that's worse than I had thought. 30-35 gallons in 17,000 gallons even assuming 6% bleach is 109 ppm so 15 ppm FC per day which is very high for an entire week. Something is very wrong in this situation -- either the CYA isn't as high as indicated (i.e. it's very low so the chlorine is getting lost from sunlight) or there are tons of organics in the pool (or algae growth).

Mike, did you ever get your own good test kit, either the Taylor K-2006 or the TFTestkits TF-100? The pool store reading for the CYA level might have been wrong. 30-35 gallons of chlorine in a week for your size pool is not normal even for a pool cleanup. Did the FC drop back to near zero within an hour or did it drop more slowly? If the FC drops quickly right away, then bacteria may have converted CYA into ammonia in the pool and that can create a HUGE chlorine demand (my personal experience about this is described in this thread). If the FC is dropping during the day but not at night, then you probably don't have any CYA in the water and the pool store reading was terribly wrong (not a surprise since they are often wrong). Has the DE in the sand filter helped clear the pool at all?

[MikeHNY]

My apologies, I hadn't been here in a while to look at responses as I have been trying to clean things up. I appreciate that there have been some new responses.

So, here are some updates:

The pool is still milky white cloudy, not green The swamp is long gone, believe me there is nothing alive in there. And the days of dumping in 5 gallons of chlorine at a time are also over, the chlorine has stabilized and I now only shock as I usually would with liquid (every 2-3 days).

For those who think the pump/filter might not be up to par, you are off base. I have super strong (actually stronger than ever) flow through the pump and back to the pool. The filter itself is a Hayward S220T and is 5 years old.

And, I am not about to change all of - or most of - the water. Nuf said about that.

Adding DE to the filter did not seem to do the trick. While I do get the 1 pound bump in pressure after adding and eventually have to backwash, then re-add, etc., this cycle has gone on for several days now (over a week) with no appreciable difference in the appearance of the water.

So I'm thinking maybe the sand does need to be changed after all? Or is that another waste of time/money? Keep in mind I live in upstate NY and swimming season will actually be over soon.

[chem geek]

Well the milkiness could at this point be a suspension where a clarifier would help, but usually that comes from things like phosphate removers and not from just clearing a pool of algae. I used GLB® Clear Blue® once with good results (I was trying out a phosphate remover as an experiment from the manufacturer and the water turned very cloudy and I needed it cleared in a hurry). Normally clarifiers aren't needed and since they don't always work they aren't normally recommended, but since filtration alone isn't helping (not even with DE), then this would be the last resort to try (the other alternative would be a flocculant, but since you say your circulation is good then a clarifier should work).

It's very unlikely you would need to change the sand unless you had terrible channeling in the filter from a serious buildup of bacterial biofilm.

[MikeHNY]

I've actually used some clarifier before I tried the DE thing. I didn't know if they were compatible so I haven't used clarifier since using the DE.

FWIW here are today's test results:
Total Chlorine 3
Free Chlorine 3
PH 7.3
TA 180
CYA 100

[chem geek]

What? Your TA is 180 ppm? What is your CH level? If it's high, then your water may be over-saturated with calcium carbonate and that's what is making it cloudy. Put your numbers into The Pool Calculator to calculate the saturation index. In your first post, you said the CH was 140 ppm. If I put those number in, the saturation index is negative, but I'm not sure I trust any of those numbers since they aren't from a proper test kit you are using yourself. If the cloudiness were to go away when you lower the pH, then that would be a sign of over-saturation with calcium carbonate -- lowering the TA level would be one solution.

Also, with a CYA of 100 ppm (are you sure it's not higher than 100?), you would need at least 8 ppm FC at all times to prevent algae growth unless you were to use a supplemental algaecide (or phosphate remover). When you first reported, the CYA was 70 ppm, so what happened? Have you been continuing to use Trichlor pucks/tabs or did you add Dichlor granular/powder? You should be using chlorinating liquid since your CYA is high and you should be diluting your water to lower the CYA level. Also, why is your TA level so high? Have you been adding pH Up for pH control (that raises TA over time in addition to raising pH)?

You never said if you got a proper test kit (either of the kits I linked to earlier). I'm thinking that perhaps your CH number might be a lot higher or your CYA might be through the roof. At any rate, if your CYA is high, don't let your FC get low -- keep it at least at 8 ppm until you know what is really going on in this pool. You should dilute the water to lower the CYA level as that will have to be done eventually anyway.

[MikeHNY]

It was a pool store test and their equipment is pretty sophisticated (and unlimited tests are free) and I trust them. I'm sure the CYA isn't more than 100 because their test obviously can read higher numbers and it has come back higher before (and on your advice I stopped using trichlor pucks). The CH is 120, also down a bit from the test several weeks ago. And, as you noted, the TA is also coming down (on purpose). By the way, I did once check the pool store test against another test at another store (different equipment) and got virtually the same results (that's why I trust them).

Changing the sand is on the agenda today.

[green to milky]

How many weeks has this been going on now? just from july 27th until today is way to long! Are you running the filter 24/7? There is no way in heck a DE or cartridge filter would take this long to clear a pool.