Turning to the hive brain yet again.
We have a basic 16x32 inground pool. I've been fighting cloudy water for weeks now. The chlorine and ph levels are fine but you can't even see the bottom at the deep end now. We had an algae bloom early in June and the water never really cleared up since. The local pool store is happy to test my water sample and sell me $200 worth of chemicals. The water clears up for a couple of days then goes back to cloudy pretty much overnight. The pool temp is 87F right now. We use chlorine pucks and regularly shock. We've used algeacide, clarifier, filter socks, floculator(sp) and filter cleaner to no avail.
I think the stuff is called flock. You put it in and all the crap settles to the bottom so you can vacuum it up.
-How hard are you shocking it?
-What chlorine level are you maintaining?
-What is your ph-? (IIRC slightly high can look murky and slightly low is clear as springwater)
-Is it possible water is getting around your filter?
Buy yourself a taylor test kit and get the hell out of the pool store test and sell loop. Test chlorine and ph throughout the day for a few weeks and log it to get an idea what is really going on with your pool. Liquid cl- is pretty cheap when its time to shock. Combine that with muriatic acid to keep the ph in check when you shock it and you are set.
I would start by posting on
www.troublefreepool.com
Its like the grmboard of pools. Just a bunch of helpful and knowledgeable people.
I would also invest in a T-100 test kit and do the testing yourself. The pool store only wants to sell you stuff you dont need.
You need to check for CC in the chlorine and make sure there are none, but you need the test kit for that.
http://tftestkits.net/TF-100-Test-Kit-p4.html
That should last you well over a year. Unless you have all the numbers for FC, CC, PH, CYA, TH its very hard to advise.
CYA is quite important as if there is none, then your chlorine might be getting zapped by sunlight.
There used to be something called 'Burn Out' for the cloudy water thing. It's probably some sort of super cancer causing agent and no longer sold. 
But I tell ya what: chasing that water pH and chlorine all the time is why I never want another pool.
High enough chlorine levels during a shock actually destroy the algae instead of kill it. Just kill it and the little algae carcasses hang out and feed the next batch of algae. I ran a commercial pool for years and never once needed a flocculant(sp?). How high is your cyanuric acid (stabilizer) level? Too high and your chlorine is locked up and doing you no good. Too low and your chlorine is getting destroyed by the sun and not helping your pool.
Also, if your PH is way off, you will not be able to get a proper chlorine reading. Make sure thats in check, I usually try and keep it around 7.2-7.3 as in my pool it usually drifts up.
Ok so my take away from this is my test kit isn't adequate. It just tests ph and chlorine levels. Both are in the normal range. Chlorine is a little on the high end of the scale and ph is a little on the low end. I'm assuming that I've just been lucky up until this year.
I quit the pool store test and sell game a couple of years ago.
All the above. Get your own test kit. There is a water clarifier that you can buy, it works somewhat. With mine, I find that after dosing it up with the chemicals and running the pump for a while. Turning off the pump and let the water settle clears it up, then go back to running the pump. I don't run the pump on mine all the time, couple hours on then couple hours off. Except when we are in it, then on while we're in the pool.
How high is high and how low is low? 
MrJoshua wrote:
How high is high and how low is low?
CL is about 2.0 and pH is about 7.4
Just right for nice swimming and crappy for easy to maintain pools. The industry has a giant hardon about >=5.0 ppm CL right now. In my opinion it comes from a mix of a few bugs that die more quickly at that level and pool service companies getting to sell you more CL and work way less maintaining your pools. The low levels are much nicer to swim in an what I shot for with the commercial pool but it required more brushing. Your levels kill germs but at best slightly slow down algae. With them that low, you really need to be sure they are never falling out in the mid day sun and not locked up in stabilizer and not working. You will probably have to stay on top of brushing and vacuuming and shock on a semi regular basis.
When was the filter sand changed?
AndreGT6 wrote:
When was the filter sand changed?
Good question but not a clue. Pool was built in 1980. The filter and pump are not original. We replaced the liner last year and the guys who did the work were very impressed with the quality of the construction. I don't imagine that this has anything to do with my current issue.
Wayslow wrote:
AndreGT6 wrote:
When was the filter sand changed?
Good question but not a clue. Pool was built in 1980. The filter and pump are not original. We replaced the liner last year and the guys who did the work were very impressed with the quality of the construction. I don't imagine that this has anything to do with my current issue.
I meant the construction not having anything to do with the issues not the sand filter
You have a sand filter? If so you could have "channeling" where tunnels have formed in the sand allowing the water to get through without filtration. You could also have a bunch of solids (leaves and such) sitting on top of the sand providing food for algae.
Re-reading your first post it sounds like it may simply bet that you have never completely eliminated your algae problem. A good shock (IIRC>30ppm for a significant amount of time with a nice low ph) will destroy all algae and anything leading to algae and leave you with a clean reset pool. There are calculators online to guide you on how much chlorine and acid to add.
First thing I would do is triple shock it, but buy your shock carefully. Chlorine levels in shock are not what they once were. If it's that cloudy and it comes back, it's more than a clarifier can handle usually. If you don't know how old the sand is, change it. It doesn't work forever. Not that difficult but you have to be careful and don't just dump the old out and the new in. There are pieces in there that break easily.
also i can't recommend enough going away from chlorine and getting a salt water system. I saved enough the first year to pay for it, and i literally do nothing to the pool anymore. It's always clear and never has issues.. I maybe spend 50 a year now. Awesome stuff.
In order to shock, you really need to know your CYA levels (cyanuric acid).
If you do not know that, you can be either wasting chlorine or not using enough. Of course wasting it is better than not enough.
Also when you shock, you have to keep the CL level as algae will "eat" it until it dies.
You will know when to stop shocking once you have no CC and can pass the overnight CL loss test. You basically check the CL level after sundown and recheck before the sun comes up (or as soon as possible), if you lost less than 1ppm of CL then you are good to go and can let the CL level drift back down.
if you have a sand filter, replacing the sand in a sand filter is easy and cheap. Just be sure to get sand for pool filters and not play sand, different qualitity. Made that mistake once, pumped sand into the pool. Changed to pool filter sand and that went away. If you have the cartridge filter, those are usually cleanable and reusable. If you don't know when whatever you have was cleaned or changed, then it isn't a bad idea to do it. Filters make a difference in the clarity of the water.
I once had an issue that wouldn't clear up otherwise and my pool store sold me some copper-something-or-other. Sounds like it may be the flock stuff, as it did exactly that - made all the crap fall to the bottom, where it was then easily vacuumed out.
switch to a salt water system?
