Filter Pressure Spiking, causes pump to lose prime

[johntc]

Hello,

I have been having an issue since last year where after about an hour of running at normal pressure the pressure in my 60 sqft DE filter grows to the max over 50 PSI which then either causes my pump to lose prime or causes a large air pocket in the pump basket. I have replaced the pump and all my filter grids. I even ran the filter without the grid assembly and that worked the pressure didn’t spike and the pump ran fine. Once the grid assembly is put in this issue starts to occur. Again all the grids are brand new and I checked the manifold for any clogs. Does anyone have any suggestions?

 

[Texas Splash]

Welcome to TFP! DE filters fill-up fast with organic material and this will continue to happen if the chemistry is off. Can you share a full set of water test results? Hopefully you have a TF-100/Pro-Series test kit, or perhaps a Taylor K-2006C. A full set of reliable test results would help.

 

[johntc]

Got my pool tested at Leslie’s the results were chl 2.6 ph 7.5 Alk 96 Hardness 150 acid 25 phos 300 and no metals

 

[Texas Splash]

Got my pool tested at Leslie’s the results were chl 2.6 ph 7.5 Alk 96 Hardness 150 acid 25 phos 300 and no metals

John, we would strongly urge you to test your own water. Local free testing is often flawed, and their advice not much better, not to mention the cost of their products, most of which are worthless. The link below shows you a comparison of those test kits I noted above. That should be step #1 for you at the moment.

As some "gee-wiz" info about your store numbers (if they were accurate), an FC of 2.6 ppm is much too low. Next to that you list acid which I'm assuming means cyanuric acid (CYA), and if it's over 100 as they say, it's way out of range and a large water exchange will be required to lower it back to around 50 or so. Once the CYA is lowered, then you would ideally perform an Overnight Chlorine Loss Test to see if you have algae, but I'm guessing you already do even if the water seems to be relatively clear. To kill & remove organics like that, you need one of those test kits and then perform a SLAM Process.

Swimming Pool Test Kits Compared

What pool test kit should I buy? Why shouldn't I use test strips? Our recommended test kits will pay for themselves in no time!

www.troublefreepool.com

 

[Texas Splash]

A lot of info you might not have been prepared for, but we see it here literally hundreds (if not thousands) of times each year. Homeowner (accurate) testing if the foundation of TFP and once you do that, pool life is MUCH easier and enjoyable. Be sure to bookmark our Pool Care Basics to see many valuable articles to help guide you. If you have questions let us know.

In the meantime, not sure how you are chlorinating (pucks, liquid, etc), but I would first get one of those kits. Once you confirm your own numbers, be prepared to exchange water if the CYA is indeed over 100. Then do the OCLT and if needed a SLAM process. We can guide you through all of that.

 

[johntc]

Thank you for that information, right now I’m using chlorine tablets to chlorinate. I’ve been wanting to balance the chemicals, but the issue is I can’t run my pump for more than an hour before that problem starts up again. I don’t want to burn out my pump. I understand what you were saying with the organic matter, but there is no buildup on the grids when I backwash or even take out the grid assembly and clean it there’s barely anything on it, it’s leading me to think it’s some sort of mechanical issue. I just can’t figure out what it is.

 

[johntc]

For my pool, not running constantly it’s not even that dirty, that’s why I can’t figure this out because there’s literally no buildup on the grids whatsoever, whatever the issue is it doesn’t let the pump run long enough to actually build up anything on the grids

 

[Texas Splash]

I just can’t figure out what it is.

Unfortunately, this is VERY common, especially with DE filters because by design they filter everything. Those grids fill up fast with transparent organics you just can't see with the naked eye. Hence, the low water flow and spike in filter pressure. Chlorine tabs are stabilized, so with each one you are increasing the CYA by about 6-7 ppm, so the CYA increases rapidly. The higher the CYA, the higher the Free Chlorine (FC) must go to keep up. See the chart below as an example of where the FC level should be according to your CYA.

 

[johntc]

Should I try to balance the chemicals on recirculation?

 

[Texas Splash]

Should I try to balance the chemicals on recirculation?

That will help to temporarily resolve the filter pressure build up, but it won't kill the organics that are the root cause of the issue. For that it all comes down to accurate testing, and that's not something you'll get at the local pool store I'm afraid. Until you can do a water exchange and get a proper test kit, I would remove any chlorine tabs for now and stick to liquid chlorine only - no CYA side effects. You have a big pool there at 40K, so I would add 3-4 gallons of liquid chlorine today, then add 1-2 gallons each day thereafter until you can test accurately.

 

[johntc]

Okay I will try that, thank you!