Filter Problems-advice needed, maybe new filter.

May 15, 2012
48
SE Texas
Seems like I've been around and around with this problem for several years. My pool water seems to have poor filtration.

First, a little back-ground.
Pool is approx. 18,000 gallons. Pump is a 1- HP whisperflo WFE-4. I recently had to install a new motor and elected to go with a 2-speed AO Smith connected to a brand new Intermatic T1000 dual timer so that I can set both the high and low speed via timers. Pump was purchased and installed by me in about 2006.

Filter, also bought and installed by me in 2006 is a Tagelus 60D sand filter. At the time this seemed like a good choice, but I'm now learning that the filter may be a little undersized for my pump. FYI the filter is rated for 60 GPM and 325# of sand.

Now, I know that a lot of people are going to tell me to check my chemistry, but I do have a Taylor 2006 test kit and I have not had trouble keeping my chemistry within the ranges. Current Chemistry today is : FC =6, CC = 0, TA = 100, CYA =40. I did not measure CH, but multiple tests usually always come back at about 200-300 and I do not have hard fill water. I normally use MOST of the principles of BBB to control water chemistry but sometimes I use powdered shock and algecides as well as pH up and pH down, but usually I try to only use Bleach, Baking Soda, and Borax along with Muratic Acid.

For this season, I did not drain and refill my pool due to excessive rain we had. I could not drain it without risking it floating. We have had enough dry weather through the years that I normally will drain the pool completely and re-fill, which takes about 2-4 days total. Also I am very constrained on time right now. I have noticed through the years that the water becomes progressively less and less clear.

I opened it to a swamp, which I was able to somewhat quickly get under control and all the chemistry in range, with the exception of the clarity.

Here is my problem. Through sites like this one and other sites I have come to the conclusion that my pump is actually pumping more water than my sand filter can handle effectively. Also when I back-wash I believe I was losing sand, which then reduced the efficiency of my filtration. I have changed the sand at least 3 times in hopes that I could achieve better water quality, and each time the water seems to improve slightly before going back cloudy.

I changed the motor to a dual speed in hopes that the slower flow would allow my filter to work better but I have not seen much improvement. I also only back-wash in low speed. I estimate that my low speed flow is in the 20-30 GPM range. I am running my pump nearly 24/7 to try and clear the water, but it remains fairly cloudy. I can just barely see the water in the shallow end ~4 ft and not at all at the deep part in the middle, which is only ~5 ft.

My water just stays cloudy, and never sparkles like it has in the past except for right after a fresh re-fill.
 
OK, That was a long winded post. Truly sorry about that, but I wanted to post any and all relevant information first.

Basically all that ends up here: I am seriously thinking about switching back to DE. I had a DE filter before this one, but changed to sand when I had to replace my pump. My old filter was ancient (1980's) and it was hard to get parts for. I THOUGHT sand was the way to go but I have been severly disappointed in the water clarity. I do have lots and lots of trees and leaves that get in the pool. Plus we swim fairly often.

I'm open to suggestions on a new filter. I like the Pentair brand so I'm consdiering one of their DE offerings. I have a top-mount valve right now but I noticed all the DE filters have a side mount valve so I'd have to change up some plumbing.

Any and all suggestions welcome, including any more possible fixes for my current sand filter.
 
It sounds as if you have something besides filter issues going on but your numbers don't look bad.

That sand filter should keep your pool a lot more clear than you're describing. One thing you're doing wrong is backwashing on low. However, I don't think that's your problem.

You obviously think a DE filter will do a better job. I'd suggest a Pentair Quad DE in the 80 to 100 sqft size.
 
The only reason I'm bw on low is because I was thinking I was losing sand on high.


Bama Rambler said:
It sounds as if you have something besides filter issues going on but your numbers don't look bad.

That sand filter should keep your pool a lot more clear than you're describing. One thing you're doing wrong is backwashing on low. However, I don't think that's your problem.

You obviously think a DE filter will do a better job. I'd suggest a Pentair Quad DE in the 80 to 100 sqft size.
 
Your filter rated at 60 GPM is a little bit small but if you run on low most of the time, it is just fine. I know this is not what you are looking for but poor water quality is almost never a product of the type of filter. What did the old sand look like when you changed it?

I almost always post this pic (taken through 7' of pool water) when someone says that sand doesn't filter well. 7-8 year old sand, never changed (and never will be) with no additives of any kind just sand.[attachment=0:cb7yditr]DSC00049.JPG[/attachment:cb7yditr]
 

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OK, I agree with you in principle, but when you're in the water and you see "particles" floating around, you know you've got poor filtration. When you've changed the sand 2-3 times with mixed results, found no leaks from laterals/up-pipe, and not losing sand back to the pool, I'm stumped on what else is left.

The only other thing I can think of is that my valve is bypassing water back to the pool but I'm not sure how to check that.

Start-up pressure is normally about ~20 psi and I usually backwash at 6-8 psi. My gauge goes to 0 when the pump is off and I have no reason to believe that it is fouled.

I do have a lot of trees and have to empty the skimmers at least 2-3 times per week, more later in the summer.

Thank you for any and all insight.
 
What did the laterals and the standpipe look like when you changed the sand? There is a chance one of them was broken during the change. If you remember them being in good shape, the multiport valve is the next suspect. If the spider gasket is faulty, it can allow unfiltered water to pass back to the pool. removal is pretty straightforward. Post back if that's something you want to look at.
 
One thing you could try is the ole sock over the return trick. That will catch anything that is making it past your filter and confirm whether or not that is the problem.

Don't ask me how you actually go about mounting a sock to the return ... but I have seen it recommended before :)
 

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Everything looked normal. If the standpipe was broken, wouldn't I see some sand in the pool? I do not.

If the valve was leaking by, wouldn't I have low pressure on the pump side, with that much water bypassing? My normal pressure at start-up is 20 and it climbs to 28-30.

duraleigh said:
What did the laterals and the standpipe look like when you changed the sand? There is a chance one of them was broken during the change. If you remember them being in good shape, the multiport valve is the next suspect. If the spider gasket is faulty, it can allow unfiltered water to pass back to the pool. removal is pretty straightforward. Post back if that's something you want to look at.
 
OK, update. I was gone until early this morning. At 4 am I went to walmart and got 13 big great value jugs of bleach. I believe they are 174 oz jugs.

I added 10 of them to the pool, which the calculator shows should increase my FC to 50. Today the water is looking much, much better, but I'm not out of the woods yet. I also checked my spider gasket and didn't find anything messed up.

I also picked up 3 bags of sand to top off the filter with. The best part is that a bunch of stuff precipitated out and I vac'd that to waste.

Here are the results:
[attachment=2:2cjgau7b]001.JPG[/attachment:2cjgau7b]
[attachment=1:2cjgau7b]002.JPG[/attachment:2cjgau7b]
[attachment=0:2cjgau7b]003.JPG[/attachment:2cjgau7b]
 
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