Sand Filter Problem?

[CHParker]

I have a Triton II TR60 sand filter that I believe is only 4 years old (we've owned the house for 2 yrs.) Our pool is 30,000 gallons, in-ground gunite. We had a problem this year in that the pool guy mistakenly opened the pool a month early (a story for another thread) so the pool had been sitting idle until one week ago today and, of course, was a lovely shade of green. Instead of waiting for the pool guy to come, I was able to clean it out and, with the help of the friendly neighborhood pool store, get the water perfectly balanced, except for one thing -- it is cloudy as can be. The water is blue, just very cloudy. According to the pool guy the filter isn't working properly and we need a new $900 DE filter. While I understand that DE may be better than sand is it normal for a sand filter to only last 4 years? If the inside of the filter is gunked up with algae, etc. can that be cleaned through replacing the sand and/or backwashing? Do we have any reasonable options other than replacing the filter?

Any help/thoughts would be greatly appreciated.

Thanks in advance,
-Craig

[nicole12]

I'm not an expert on cloudy pools sounds more like a water balance problem.

As far as the sand filter goes I have taken apart my sand filter more times than I would have liked to do it. There really is nothing to it besides the pain of removing the wet sand. I have a 150lb sand filter and it took about 1 hour to remove the sand, standpipe and laterals, and then I rinsed it out with the hose. Inspected the laterals and standpipe, put them back in, covered the top of the standpipe so no sand would enter into it made sure it was straight and then put new sand back in the filter. Put the valve assembly back on and I was done, nice new clean sand filter.

[Poconos]

I think Nicole is right. Most likely a water chemistry issue. Sand lasts a long time, I'm on my 10th season. Unless you goop it up somehow there is no need to change. There is a possibility the cloudiness is stuff in suspension that is too small to be caught by the filter but I doubt that. If that is the case there are tricks to add DE to sand filters to handle those issues. Check the water forums for more info and post your numbers. Free or Total Chlorine (FC-TC) Combined Chlorine (CC) if you can measure that, pH, Total Alkalinity (TA), Calcium Hardness (CH) and Stabilizer aka Cyanuric Acid (CYA). OR...post what you can measure and if you can't test all that stuff then take a sample to a pool store. Just stay away from the cash register and turn off your receiver (ears) to what they may tell or sell you.
Al

[CHParker]

Thank you for your replies. Let's assume there is a sand problem, could that be causing the cloudy water? If it is the sand, would new sand clear up the problem or is a new filter required? Would backwashing the filter eliminate any potential sand problems?

Thanks in advance.

[ScottS]

If you haven't backwashed your sand it wouldn't hurt to do it and may be needed. Backwash it until dirty water stops coming out, rinse, backwash again, and rinse.

Did the filter work ok last year? If so an algae episode of a couple of weeks shouldn't affect the sand to the point of replacement, if at all after it is backwashed.

If your numbers are good it could take some time for the water to clear. It took mine about a 1 1/2 weeks to go from cloudy blue to crystal clear. It is also very important to make sure you get all of the junk off of the bottom by a manual feed vac, or whatever means you have. I would also suggest using a skimmer sock (some people use pantyhose) as they work well for catching small debris.

I wouldn't change the sand yet and I certainly wouldn't be replacing the whole system. Cloudy water can mean many other things other than a filter replacement. Be patient with it, keep your numbers right by following Al's advice, and remember to run the filter 24/7 until all problems have ceased.

Good luck.

[aquarium]

If it's only been running for a week, then I'd let it run another week before doing anything drastic. Keep the chlorine level high at all times. How long per day are you running it? You might try a couple of 24 hours a day runtime to force it to clean things up. Seeing as how this poolstore is trying to sell you expensive things you probably don't need, I'd be very wary of their advice and test results.

[Watermom]

I'm gonna echo what Poconos said above --- I also don't think it is a sand problem. You can certainly try backwashing the filter and then when it is clean, note your filter pressure. Do the DE addition - slowly - only adding enough to raise the pressure 1 psi. It may take a half hour or so to see any change in pressure. Adding just a little DE to a sand filter helps it to catch and filter out the smaller stuff that the sand alone might not get. It might be the very thing to solve your cloudy water problem. Also, while you are trying to clear it up, run the pump 24/7.

Post your numbers and somebody here can take a look and see if there is something else we can offer to help.

[CHParker]

I have been running it 24/7 for the past week along with a Dolphin (not 24/7 but fairly often) and there is definite improvement. It went from deep green to blue, albeit cloudy blue. After testing the water repeatedly, every number was ok except CYA which is very low. According to the pool guy the filter is running extremely slowly which is why he is hot to replace it. He says it may work (at clearing the water) eventually but could take a few weeks. Just to be clear, it isn't the pool store that wants my filter replaced.

The pressure on the filter is normal (about 20lbs) if that makes a difference and the filter worked fine last season. Could there be a filter problem independent of the sand condition, or is that unlikely?

Thanks for the great responses.

[KurtV]

CH,
Please post your test numbers as Poconos suggested. Your problem almost certainly lies, at least mostly, with your chemistry.

That said, the TR60 is a pretty small filter for a 30,000 gallon pool. What is the size of your pump? There's some possibility you're overdriving the filter which is causing channeling in the sand. That would allow at least some of the water to flow through those channels, essentially without being filtered at all.

[matt4x4]

Ok, here's the scoop, you get an algae bloom, then kill it, it becomes VERY fine microscopic dust, once you start filtering, let your filter collect it and collect it and collect it, DON'T backwash unless your pressure goes up over 6lbs more, a dirty filter works better than a clean one. Most of you filtering abilities will happen after 4 days of this and your pool will start to show improvements the longer you can keep the filter dirty.
Running an automatic vac during an algae kill off is ok to do, but it will continually disturb the fine particles. If you have a bottom drain, it would be much more beneficial to use it over a vaccum for picking up the settling dust. with an auto vac, you think you're sucking up what's dropping out, but really you're just stirring 90% of it back up into the water making it take THAT much longer to filter it all out.
I'd recommend that at the "milky stage" you add floculant and follow the instructions on the bottle, within a day or two all the dust will have settled into "wet dust bunnies" in the bottom of the pool.
if you have the luxury of being able to vac to waste, do so with your MANUAL head at this point, using the auto cleaner will just break up those nice clumps again and you're back to a cloudy pool.

Another trick is to add DE to your sand filter (start with 1/2 cup, and keep adding 1/2 cup until your pressure rises 1-2lbs maximum) - NOTE - wait 1/2 hour before adding more...., it essentailly mimicks a dirty filter, giving it better filtering properties through coating the top of your sand with a much finer medium, allowing much better filtration.

As for your sand being bad - I'd say - no, sand doesn't really go bad unless you continually dump chemicals into your skimmer, even then, the chances are slim to none. This is just the natural process of cleaning up a pool, DE filters work faster during these stages of cleaning up, but as stated above, you can mimick DE filteers through the proper use of a sand filter and a little cheating by adding DE and using flockulant - all in all, proper procedures plus cheat reduces cleanup time by almost 50%.