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Thread: Newbie with a DE filter problem

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    Newbie with a DE filter problem

    I'll start by saying I have very little idea of what I'm doing, so it's entirely possible this problem is of my own making. In the interest illustrating my potential stupidity in order to fix the problem, this may be long.

    I have an inground pool with a Purex Triton FNS Plus 48 DE filter. (We just bought this property a few months ago and the pool has not been open in 4 years.) I started opening the pool a few weeks ago. The pool was more like a pond, so I went with maintaining a high shock level of chlorine, scrubbing the walls and bottom, and vacuuming the pool to the try and clear it up. It cleared to a cloudy slightly green color and wouldn't go any further and it was around this point that I realized the DE I put in after backwashing was blowing back into the pool in great plumes. I took the filter apart and found a couple of the grids had small holes and the top manifold was cracked. Rather than mess with trying to replace the individual grids and the manifold, I ordered a whole new grid assembly.

    Got the grid assembly, installed it, and put in the what I thought was the recommended amount of DE. The pool place told me to use a coffee can. My filter should have about 4.8 pounds of DE and I was told to use "about 10" scoops from the can, and that's what I did. The psi after coating was at 18. The next morning, I saw an improvement in the pool water. The day after that, I saw an even greater improvement. The water was still cloudy, but I could see the bottom clearly enough to know the vinyl liner has a pattern on the bottom. (And that I did a horrible job vacuuming when I couldn't see...)

    So, I vacuumed again. Whenever the psi got above 30, I backwashed and after each time I backwashed, I added about 2 pounds of DE (as recommended by the pool place). In that first vacuum session when I could see the bottom, I backwashed about 6 times. The next day (which brings me to yesterday), I noticed the water was clouding up again, but I thought it was because I put the Tiger Shark robo vac in the pool that morning. I took it out and put it away. The pressure wasn't high on the filter, so I decided to vacuum manually until it was high and then backwash. As I was vacuuming, I noticed the water from the jets was blowing in the same color as the dirt on the bottom and that the pool was getting worse. I stopped vacuuming, backwashed the filter, added another 2 pounds of DE, and called it a day. Before going to bed last night, I checked the filter, found the pressure was up, so I backwashed and added another 2 pounds of DE. I checked the jet and found a huge plume of the clean DE blowing into the pool. This morning, the water is right back to the cloudiness it was before I installed the new filter grid.

    What have I done wrong and how can I fix it?

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    Richard320's Avatar
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    Re: Newbie with a DE filter problem

    Welcome!

    First question.... were these 1 lb coffee can scoops? Or 2 pounders? I'm wondering if you didn't overload the filter and the pressure cracked something.

    There's also the possibility that a seal in the backwash valve has gone bad and so some water is backwashing when it should be filtering. The water's going to take the path of least resistance.

    Bottom line, you're gonna have to open it up again and inspect things. Even a small " tear in one screen or a crack somewhere will let a whole lot of DE out.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Re: Newbie with a DE filter problem

    The "can" is a two pounder, but I use only one scoop when adding DE after the backwash.

    I'm going to open it up to see what's going on. With what I described, is there any chance I didn't break something?

    If the backwash value was sticking, would that allow DE to go back into the pool when I add it after backwashing? I have had some trouble with the value and have to double check that no water is coming out of the backwash tube after I put it back on filter because I have had a couple of instances where the valve stuck a bit and it was filtering with a trickle of water going out the backwash tube.

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    Re: Newbie with a DE filter problem

    Quote Originally Posted by Wildcat180 View Post
    The "can" is a two pounder, but I use only one scoop when adding DE after the backwash.

    I'm going to open it up to see what's going on. With what I described, is there any chance I didn't break something?

    If the backwash value was sticking, would that allow DE to go back into the pool when I add it after backwashing? I have had some trouble with the value and have to double check that no water is coming out of the backwash tube after I put it back on filter because I have had a couple of instances where the valve stuck a bit and it was filtering with a trickle of water going out the backwash tube.
    If you have a multiport valve,


    the spider gasket is prone to failure.



    There are instructions on here somewhere, and plenty of youtube videos that show how to do it.

    If you have a push-pull valve


    the O-rings can get stiff and brittle, and you can get corrosion inside that will chew them up. Conceivably, they could send some water the wrong way inside the filter and then it gets mixed and pushed out.

    Cracks or tears are more likely, though.

    Not an approved repair, but.... my inlaws had a small tear in a grid. Being thrifty, my mother in law stitched it up with some dental floss and my brother in law sealed that area up with some silicon gasket goo aka RTV. So they lost 2 square inches of filter surface, but no more DE leaked through. Lasted several years, too.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Re: Newbie with a DE filter problem

    Thanks for the info! I have a multiport valve, so I will be sure to look into replacing the gasket.

    I opened the filter up and found that the screen on the tube sticking out from the top of the manifold came off and that's why the filter was blowing dirty water and DE back in last night. Before I opened it up, I backwashed it really good (backwash to rinse, then back to backwash about 6 times before the water was clear) and when I opened it, there wasn't much DE in places there shouldn't be DE. The fins are all in good shape, which they should be, being brand new and just installed 3 days ago. Whew! I hosed out the grid and closed everything back up. It's back up and running and seems to be filtering nicely. The only thing is, the pressure seems to go up rather quickly, like in a matter of 3 hours it's up 10 psi. The pool is dirty, so maybe it's just doing its job a little too well?

    I'm planning on picking up a kitchen scale this evening to weigh out the DE to make sure I don't put too much in. This coffee can stuff is too much guess work. If I start out with 4.8 pounds of DE and then backwash (going back and forth from backwash to rinse a few times), how much DE should I add when I'm ready to go back to filter?

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    Re: Newbie with a DE filter problem

    Quote Originally Posted by Wildcat180 View Post
    Thanks for the info! I have a multiport valve, so I will be sure to look into replacing the gasket.

    I opened the filter up and found that the screen on the tube sticking out from the top of the manifold came off and that's why the filter was blowing dirty water and DE back in last night. Before I opened it up, I backwashed it really good (backwash to rinse, then back to backwash about 6 times before the water was clear) and when I opened it, there wasn't much DE in places there shouldn't be DE. The fins are all in good shape, which they should be, being brand new and just installed 3 days ago. Whew! I hosed out the grid and closed everything back up. It's back up and running and seems to be filtering nicely. The only thing is, the pressure seems to go up rather quickly, like in a matter of 3 hours it's up 10 psi. The pool is dirty, so maybe it's just doing its job a little too well?

    I'm planning on picking up a kitchen scale this evening to weigh out the DE to make sure I don't put too much in. This coffee can stuff is too much guess work. If I start out with 4.8 pounds of DE and then backwash (going back and forth from backwash to rinse a few times), how much DE should I add when I'm ready to go back to filter?
    80% of what you installed with spotless grids after a backwash.

    And DE filters filter really well, so a dirty pool can easily clog them within hours.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Mod Squad zea3's Avatar
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    Re: Newbie with a DE filter problem

    DE filters work very, very well. The downside is they get dirty very, very quickly when you are clearing a swampy pool! Backwash when you have a 20% pressure increase, and recharge the DE. If you are having to backwash daily you may want to open the filter and hose off the grids every few days until the pool is clear.
    TFP Moderator
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    Re: Newbie with a DE filter problem

    Today alone I had to backwash 3 times after I opened the filter. The pool is dirty, but it's not longer swampy. The water is cloudy, but I can see the bottom just enough to make out the pattern on the bottom of the liner in the shallow end. If I should be backwashing when the pressure increases by 20%, I should be backwashing more often. I've been doing the backwash when the pressure goes to just under 30 psi, which the pressure right after adding the fresh DE is around 18-20 psi. Basically, when I notice the flow of the water back into the pool slows is when I backwash. At this rate, I feel like I should buy stock in the brand of DE I've been using! I think I'm going to replace the pressure gauge, for good measure. We bought the house a few months ago ad the previous owners hadn't opened the pool for more than 4 years. The filter and everything sits outside, so it couldn't hurt to change it right?

    80% of 4.8 lbs is just over 3 lbs, and I've been adding around 2. Here I was worried about using too much and it turns out to be too little. The pool place my husband and I went to when we opened the pool three weeks ago told us the 25 lbs bag of DE should last the whole season. We're about to finish the second bag.

    You guys have been so helpful. I really appreciate it.

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    Richard320's Avatar
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    Re: Newbie with a DE filter problem

    Quote Originally Posted by Wildcat180 View Post
    Today alone I had to backwash 3 times after I opened the filter. The pool is dirty, but it's not longer swampy. The water is cloudy, but I can see the bottom just enough to make out the pattern on the bottom of the liner in the shallow end. If I should be backwashing when the pressure increases by 20%, I should be backwashing more often. I've been doing the backwash when the pressure goes to just under 30 psi, which the pressure right after adding the fresh DE is around 18-20 psi. Basically, when I notice the flow of the water back into the pool slows is when I backwash. At this rate, I feel like I should buy stock in the brand of DE I've been using! I think I'm going to replace the pressure gauge, for good measure. We bought the house a few months ago ad the previous owners hadn't opened the pool for more than 4 years. The filter and everything sits outside, so it couldn't hurt to change it right?

    80% of 4.8 lbs is just over 3 lbs, and I've been adding around 2. Here I was worried about using too much and it turns out to be too little. The pool place my husband and I went to when we opened the pool three weeks ago told us the 25 lbs bag of DE should last the whole season. We're about to finish the second bag.

    You guys have been so helpful. I really appreciate it.
    Once you get the swamp cleared, a bag will last the whole season and then some. I've never had to backwash more than twice in a calendar year, and my pool is never closed.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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