Filter not filtering?

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rednekk

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Sep 17, 2008
20
Hello, I'm hoping maybe someone can shed some light on a problem that I can't seem to figure out.

Beginning about halfway through last season, I began to have a problem with algae. Every day or 2, I would find a few small patches of algae in the pool and would have to vacuum. Multiple water tests (my own and a local pool store) showed no problems with water chemistry. I’d shock and sometimes be ok for a few days, and sometimes it made no difference at all. Also, I struggled with mild cloudiness throughout the season. We went on vacation for a week in late August and when we came back, it was completely green to the point that we couldn’t see the bottom. Frustrated, I just closed it up for the winter.

Last week I removed the cover, and obviously it did not get any better. Long story short, in the past week I have put 8 pounds of shock into the pool, and all it has done is change it from emerald green to an olive drab color. I can see pretty heavy particulate matter suspended in the water as well.

Now, for my filter question – I have good suction and plenty of pressure at the outlet. I’ve run the filter continuously for the past week, backwashing twice a day. When I backwash, I get some green water out, but only for 5-10 seconds, then it runs clear. It seems to me that I should be getting a lot more nastiness out of there when I backwash. Could a failed spider gasket be allowing some or most of the water to bypass the filter sand? Anything else I should be looking at?

I’m likely going to drain and refill the pool regardless, just to start with a clean slate, but if it is the filter that is causing this problem I’m just going to wind up with the same issues this year. Any input will be greatly appreciated. Thank you.
 
Welcome to the forum. :wave:

We frequently get posts similar to yours. 95+ percent of the time it is water chemistry and not the filter.

So your first task would be to learn the water chemistry better, get a good test kit, and then SLAM your pool.

Read "The ABC's of Pool Water Chemistry" up in Pool School....that's a great starting point.

No filter of any kind or size will filter live algae from your pool. You must kill it completely with the SLAM process and then maintain your FC adequately throughout the swim season.
 
Welcome back! Your last post was way back in 2008. You should've come back last year, we coulda gotten that pool sparkling a whole lot easier then.

Mistake number one: "Multiple water tests (my own and a local pool store) showed no problems with water chemistry." You need a good kit and learn to trust your own results.

Mistake number two: "I’d shock and sometimes be ok for a few days.." We don't use that s word around here. The pool store will have you give it a one-time liner-bleaching megadose of chlorine and hope that kills it all. It seldom does, as you've experienced. No, it takes a high, but monitored, chlorine level for an extended period of time to kill off all the algae, all of it, every bit.

There's a really high probability that you've been sold buckets of pucks and bags of "shock" and now your pool water has too much cyanuriuc acid aka stabilizer aka CYA. That makes it difficult to kill the algae.

For now, tell us what kind of test kit you have, and then go study pool school a while, until you feel like :crazy: Then look at something less taxing. Here's a few:

First Time Shocking with Bleach
Pretty black pool
A little encouragement for those with algae and new to BBB
Frog Filled Green Swamp to Oasis---Work in Progress!!!
Before and After Pool Pics
Before and after!
A final picture set of how well the BBB method works!
 
Thank you for the input – I’ve read over the Pool School before, and I will go through it again. Maybe this will be the year that I jump into the BBB world.

What are your thoughts on any possible filter problems? Should I be seeing more dirty water when I’m backwashing? At this point, I think for me the best option for clearing it up is going to be a drain and re-fill. I can be starting clean in 1 weekend instead of the weeks it would take to try to clear up what I’ve got (besides, as it warms up, I can’t stand the smell of this water – it smells like a stagnant swamp mere feet from my back door). I just want to be on the right track once that’s complete.

Again, thank you for the input thus far.
 
The filter won't get rid of the green. The stuff is too fine. It has to die and clump to get strained out.

That being said, maybe the sand is chanelled or clumped, if you're not seeing much in the backwash. You could try a deep cleaning just to put your mind at ease. Wear old clothes and shoes.

If you've been following the pool store advice and dumping in all kinds of powders and potions, draining it will likely be necessary, but the only way to be absolutely sure is by testing it. Still, if you're in a hurry and don't mind draining, that will get you off to a good start. Be aware, you have to leave some water in the pool, lest the liner shift or shrink. So even if you do drain it, you'll still have some cruddy water mixed in that will need treatment, which will require a test kit. You might notice a pattern, here...
 
Thank you. I will definitely be picking up a new test kit this year. The one I had been using was decent, but I’m just about out of reagents, so it’s a good excuse to spring for one of the really complete kits. I’ll need to do some research on that sooner rather than later.

I haven’t been throwing all sorts of pool store advice and chemicals into the pool. I just take advantage of their free testing and use the results (and mine) to make my decisions on what the pool needs.

A question on draining the pool – my plan was to drain it completely, scrub it down with bleach and begin to re-fill immediately. Am I still taking a chance with the liner by draining fully, if it’s only going to be empty for a few hours? If it matters, the pool and liner are 6 years old and it has never been drained.

Thanks again.
 
rednekk said:
A question on draining the pool – my plan was to drain it completely, scrub it down with bleach and begin to re-fill immediately. Am I still taking a chance with the liner by draining fully, if it’s only going to be empty for a few hours? If it matters, the pool and liner are 6 years old and it has never been drained.
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I've never done it, but I have read enough horror stories here. Let's wait and see if anyone can give you any firsthand reports.
 
I would not drain a vinyl liner pool 100%. You are at risk of the liner shifting even if it is empty for a short time. You should leave at least a foot of water in the shallowest part of the pool in order to keep the liner in place. If you are in an area with a high water table you will be at risk of floating the liner if you drain too much water.
 
Thank you for the advice. I just noticed that my signature incorrectly identified my pool as an in-ground. It is actually a 27' round 54" deep above ground pool which is slightly set into the ground on one end. It is set in approximately 24" below grade for about 1/3 of its circumference. Not sure if that changes anything.
 
I know practically nothing, working on my 3rd summer with a pool, but when I bought my house the pool was more than disgusting. It sat untouched for over a year, no one living in the house at all, some time during that a storm blew a tree, well about half a tree, into it pulling the cover and about 20 sand bags holding the cover into the pool. What did the bank do that owned it, through a new cover over top and just left everything sit in the bottom. I have no idea when any of this happened, they told us nothing, when we removed the cover all we saw was black water and millions of tadpoles. We found out about the other cover, sand bags, and tree by pulling them out. The water was disgusting and smelled like sewage, also it was my first experience with a pool, and not knowing anything I thought screw it I am renting a trash pump (there was no pump or filter, I had them ordered but not came yet) and just draining everything out. I emptied ever drop of water out and scrubbed the floor and walls, took a few day but we got all the gunk out, after draining the water we shovel out 1 1/2 tons of black sludge (I know because when I took it to the dump that is what they weighed it at). Point of the story is that before I could start filling it up again I noticed the liner starting to shrink and pull up from the bottom, we got lucky when we got new water in the liner stayed in place and we were able to keep it, but it has always felt just a bit odd, there are wrinkles all over and in some place squishy pockets of either air or water not sure. The liner is holding up and I can deal with the wrinkles until I get the money for a new liner, but I feel it needs a new liner because of this, so my point is I guess, if I did not have to drain it and knew what I know now I would not have
 

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I'll attest to the draining difficulties. A connection from a bottom drain unsealed over the winter, drained all water to about a foot and sat taht way over the winter. Last week, I drained the remaining, scrubbed it with a brush and garden hose and refilled. Now my pool is leaking and I have no idea why. Best to avoid!

I've gotten into the habit of trying to BBB method and supplementing with pool store supplies. its not worth it. Have patience and follow the BBB method like a bible. Test your CYA and keep your Chlorine in the recommended levels. The cloudiness will go away! After that, then you can worry about your filter. If it is damaged, you'll likely be getting sand in your pool. It is a sand filter, right?
 
rednekk said:
Thank you for the advice. I just noticed that my signature incorrectly identified my pool as an in-ground. It is actually a 27' round 54" deep above ground pool which is slightly set into the ground on one end. It is set in approximately 24" below grade for about 1/3 of its circumference. Not sure if that changes anything.
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You should still keep about a foot of water in the bottom to keep the liner from shifting. An above ground pool liner is just as likely to dry out and shrink when empty as an inground liner. You don't need to worry about water tables with an above ground pool, but I will say this; water provides most of the structural integrity of your pool. The side walls are thin and fairly flimsy. When the pool is empty a good gust of wind can blow in the sides and cause the pool to collapse. When the pool is full the pressure of the water against the side walls makes them able to withstand much stronger winds. Think of it like a soda can. Its much easier to crush an empty soda can than a full one.
 
Well, it was a busy weekend, which unfortunately yielded very little in the way of results. We drained a little more than half of the water out, by vacuuming to waste. I jumped in (let me tell you how much fun that wasn't) and scooped out ALOT of leaves, then vacuumed again. I think I got most of the debris off of the bottom. I say "think", becuase I wtill cannot see the bottom. The water is a light milky green, and completely opaque.

With the water at half-depth, I added 2 gallons of 12.5% bleach, which immediately brought my FC level to 2.0. The chlorine smell was very strong, to the point of burning your eyes from several feet away. 6 hours of run time later, the FC was undetectable, and the water looked absolutely no different. I wasn't expecting miracles, but some progress in the right direction would have been nice. I wasn't able to do any other testing due to aforementioned clarity issues.

Next step? Current plan is to drain it down another 12" or so and try again. That is, of course, unless you fine folks have some better ideas.

As always, any input is appreciated.
 
rednekk said:
Well, it was a busy weekend, which unfortunately yielded very little in the way of results. We drained a little more than half of the water out, by vacuuming to waste. I jumped in (let me tell you how much fun that wasn't) and scooped out ALOT of leaves, then vacuumed again. I think I got most of the debris off of the bottom. I say "think", becuase I wtill cannot see the bottom. The water is a light milky green, and completely opaque.

With the water at half-depth, I added 2 gallons of 12.5% bleach, which immediately brought my FC level to 2.0. The chlorine smell was very strong, to the point of burning your eyes from several feet away. 6 hours of run time later, the FC was undetectable, and the water looked absolutely no different. I wasn't expecting miracles, but some progress in the right direction would have been nice. I wasn't able to do any other testing due to aforementioned clarity issues.

Next step? Current plan is to drain it down another 12" or so and try again. That is, of course, unless you fine folks have some better ideas.

As always, any input is appreciated.
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Cloudiness isn't really a good judge of how much you've progressed.

Go look at your CYA test vial. The spacing on the lines is not even. To reduce the suspended matter from 100 to 60 is roughly the same as 40 to 30 - 4X difference!

The SLAM works by keeping the FC high enough to kill algae faster than it can reproduce as consistently as possible. Six hours is probably too long between doses. If it smelled that strongly, it was probably all gone within the hour.

Keep dosing, keep vacuuming, keep brushing, keep filtering. It didn't get that way in a couple days, it won't clear in a couple days. After a few years of reading these stories, I'll tell you that almost no one is impressed the first couple days. It may go green to grey, but it still takes a while to look better.

First Time Shocking with Bleach
Pretty black pool
A little encouragement for those with algae and new to BBB
Frog Filled Green Swamp to Oasis---Work in Progress!!!
Before and After Pool Pics
Before and after!
A final picture set of how well the BBB method works!
 
Ok, thank you for the encouragement. Will it be beneficial to me further lower the water level? My thought process on this is that if I have only 25% of the water, a set amount of chlorine should have 4x the potency - is that correct?
 
rednekk said:
Another question if you don't mind - how can I determine/estimate my CYA level for SLAMming purposes? I can't see the dot in the bottom of the tube even without reagent.
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Run the sample water through a coffee filter, and then make sure you can see through it in the view tube all the way. Then mix up your test solution and test it. If it clouds up before you get to 100, don't just dump it. There are directions here for dealing with super-high CYA. Post 8, step 9
 

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