Replaced my DE filter and the pressure is much higher now

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M

mac4lyfe

0
LifeTime Supporter
Jun 8, 2007
217
Houston, Texas
I use to have a Nautilus 48 DE filter but it started to corrode when I went to a SWG. So I replaced it with a Hayward DE 48 (4820). My old Nautilus use to get pressure around 20 psi and I would backwash at 30 psi. This filter goes up to about 30 psi immediately and will go up to 40 psi after about 30 minutes. If I backwash, it will go back to 30 but then 40psi 30 minutes later.

This has slowed my flow rate down considerably to the point the SWG no flow light comes on. Now I also changed my valve to a Hayward SelectaFlo multiport valve. It is a 2' line to the pump where I use to use 1.5' with the old valve. The return pipe is now 2' instead of 1.5" but only about 4 feet.

I have a Challenger 1.5 HP pacfab pump for a 30,000 gallon pool. Is the new DE48 filter too small? is my pump too big or too small? I'm confused what's the problem.

One other thing is that if I don't run through the filter and return directly to the pool, the flow is good to the pool. It's only when I go through the pump where the flow slows down and not much circulation in the pool.???
 
Sounds like it was plumbed backwards. Are you sure the pump output is plumbed to the filter intake? The ports are labeled Pump, Return, and Backwash as I recall.

If you did, the first thing to do is to try to get the DE out of the grids. If running in Rinse results in a large amount of DE being flushed and is visible in the view bottle located near the backwash port, the insides of the grids got your DE charge. You will likely need to do it a couple times and remove the grids, hose them off and then rinse again.

After you get as much DE out from the insides, then fix the plumbing. After it dries, backwash again. If it's clear, recharge the filter.

Scott
 
PoolGuyNJ has covered the most likely possibility. If it turns out that it is plumbed correctly, there are a couple of other things you can check. One would be to make sure that no suction/return valves got left in the off position accidentally during the replacement.

When you haven't been filtering for a while, debris can accumulate in the water, causing DE filters to require quite a lot of backwashing over and over again until the water clears up. Occasionally, this can happen with only particles too small to be seen, so the pool might look completely clear even when this is happening.
 
The valve inlet's/outlet's did seem backwards from the labels that came with it. I installed it based on what was stated. I'll have to double check. It has 2 inlets one on each side where you can install and you cap off the other side but it seemed very odd to me.

I also have very little DE on the grids as I opened it up, removed them and sprayed it all off and the pressure still started at 30psi while my old filter was around 20psi.

Thanks for the advice guys. I will recheck everything.
 
It looks like the following picture

wolthuis.aspx


The pump inlet is the one on top. The waste is in the middle and the return is on the bottom. There is another pump inlet on the other side (so you can install from either side). I capped that side off.

When I bypass the filter, I'm getting excellent flow to the pool but as soon as I try and filter the water, the flow to the pool goes down drastically as if there's a clog in the filter or that the grids are too tight. Could these new filters be much more tight than my old ones? I remember a couple of years ago, I changed my Nautilus grids and the pressure was real high as well. I interchanged a couple of them with a couple of my old grids and the pressure was normal.??
 
If the pressure rises that quickly after backwashing the grids have been clogged and need to be cleaned. A 1.5 full rated challenger pump is too large and high head for optimum performance with that size filter. Is it the same pump you had for the old filter?
 
It's a new filter.

When you opened it, you said there was little DE. Had you backwashed first? A 6 pound charge of DE would leave a substantial cake when opening it up if you didn't backwash 1st.

Were you able to see the framework inside the grids?

Did you use reducer bushings or is everything 2" plumbing?

If you drain the tank and disconnect the multiport and slid the tank back, with the MPV in filter, turn on the pump to verify water is coming out the lower connection that would go in the filter then turn it off. Now switch to Backwash. The water should come out the upper connection.

Check the tank's connections for blockages. Remove the grid assembly. Drop the male end or an extension cord down the stand pipe. It should be visible in the upper multiport connection.

With a shop vac, blow air in the lower multiport connection. Listen for obstructions.

With the shop vac, blow air in the port on the grid that gets set on the stand pipe and listen for obstructions.

If everything is clear there, reassemble the tank and slide it back into position to reattach the multiport.

Remove the screws on the top of the multiport and lift the key assembly off. Use a firm twisting/lifting motion to walk it up. Inspect carefully, noting the water path when you look at the key assembly and valve body. It's possible the factory put the handle on 180 degrees off. If it is wrong, you will need a second person to press down the assembly so you can remove the handle pin and turn the handle 180 degrees and reinsert the pin. Then reassemble the key assembly to the valve body, being certain to orient it correctly.

I don't believe the pump is too much for this filter. Max flow allowed is 120 GPM. Your pump on it's best day can't do 100.

Have you checked the impeller?

Scott
 

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renovxpt said:
If the pressure rises that quickly after backwashing the grids have been clogged and need to be cleaned. A 1.5 full rated challenger pump is too large and high head for optimum performance with that size filter. Is it the same pump you had for the old filter?
Click to expand...
Yeah, this is the same pump I had with the Nautilus 48 filter previously. I never had any issues with that filter with this size pump. I've opened the filter and hosed down the grids to wash DE and dirt off the grids and the pressure still started high (around 30psi). My pool water is fairly dirty and it could be clogging the grid fairly fast. I think I'm going to test the system without the grids in place and see if the flow back to the pool is sufficient or if it's clogged. If so then maybe something is wrong with the valve or the connections to the filter.

Can I damage the filter case by running the system without the grids in place? I wouldn't think so??
 
PoolGuyNJ said:
It's a new filter.

When you opened it, you said there was little DE. Had you backwashed first? A 6 pound charge of DE would leave a substantial cake when opening it up if you didn't backwash 1st. Yeah, I backwashed first then sprayed all the cake off the grids when I first used it. I've subsequently haven't used any DE as I've been trying to figure out what's causing the high pressures.

Were you able to see the framework inside the grids? Yep, I've taken the grids out to spray down on several occasions (sprayed DE off and dirty). Everything looks pretty good but I haven't taken it apart piece by piece yet.

Did you use reducer bushings or is everything 2" plumbing? Everythings 2" from the pump to the filter until it goes back to the return which reduces to 1.5". My old setup was all 1.5"

If you drain the tank and disconnect the multiport and slid the tank back, with the MPV in filter, turn on the pump to verify water is coming out the lower connection that would go in the filter then turn it off. Now switch to Backwash. The water should come out the upper connection. Excellent idea, I'll attempt as soon as I have time.

Check the tank's connections for blockages. Remove the grid assembly. Drop the male end or an extension cord down the stand pipe. It should be visible in the upper multiport connection. Another excellent idea. Will test as soon as possible.

With a shop vac, blow air in the lower multiport connection. Listen for obstructions.

With the shop vac, blow air in the port on the grid that gets set on the stand pipe and listen for obstructions.

If everything is clear there, reassemble the tank and slide it back into position to reattach the multiport.

Remove the screws on the top of the multiport and lift the key assembly off. Use a firm twisting/lifting motion to walk it up. Inspect carefully, noting the water path when you look at the key assembly and valve body. It's possible the factory put the handle on 180 degrees off. If it is wrong, you will need a second person to press down the assembly so you can remove the handle pin and turn the handle 180 degrees and reinsert the pin. Then reassemble the key assembly to the valve body, being certain to orient it correctly. Wow, this would be a huge factory error but very plausible.

I don't believe the pump is too much for this filter. Max flow allowed is 120 GPM. Your pump on it's best day can't do 100.

Have you checked the impeller? I'm getting excellent flow to the pool when I bypass the filter. The pump is working very well and my my outlets to the pool and skimmers are functioning very well when I bypass. My SWG flow rate looks good when i bypass but it goes to low flow when I filter which also points to some type of obstruction to the filter. Maybe the handle is off but I'd think the pump would dead head which it isn't. I'm getting some flow when I filter but it's much lower than when I bypass.

Scott
Click to expand...
Wow - you have some excellent ideas that I didn't even think about. Your a great troubleshooter :)

I really appreciate everyone's help/contribution. I'm sorry I haven't been able to update the status quick enough as my work has been very busy the past few weeks but I'll do some more testing tomorrow afternoon. Thanks much :goodjob:
 
UPDATE: I ran the pump through the filter without the grids in place and it ran well so I took the grids apart to inspect and they were extremely dirty. I couldn't tell they were that dirty by just removing the entire grid. I had to take them apart to see how much dirt was on the inner side of the grids. I did a thorough cleaning of the grids and replaced and the pressure is now normal and the flow is good.

I normally can just rinse the outside of the grids and backwash in order to clean the grids sufficient. This is the first time I've ever had to take the grids totally apart just to bring the pressure down to a manageable level.

Thanks for all the help and suggestions. I'm so relieved to not have to take the system apart.
 
Good job!

The old school of thinking has always been that if a DE filter pressure rises 10psi in less than 24 hours after backwashing the grids need to be cleaned. It has also been 2gpm per sqft or in your case a max flow rate of 96gpm. I don't know where Scott came up with 120gpm for that filter but it might be a new way of rating the flow similar to uprated pumps. It hard to see thru the marketing hype and would be much easier if 1hp meant 1hp. In general it used to be accepted that medium head pumps worked better on DE filters than high head. Either way you seem to have solved the problem. Good job!
 
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