Replacing cartridge filters

Oldpool4629

Member
Feb 8, 2016
18
Dallas, Tx
Firstly, love this site! I have learned so much and am trying to keep my pool clean personally using PoolMath. I'm trying to replace our filter cartridges. We bought this house with the pool and no background info on any of the equipment. When I look at this old, cracked by heat label, it looks like we have the C4520BH (or C4520LBH) model. However, I'm pretty sure the filters inside are the ones for the C5520BH model. If you look really closely, there seems to be a mark on the box that says C5520BH but the number on the side of the Serial no. box is C4520LBH. The difference between the two filters is their height. The CX875RE (Unicel C-7489) are 25.5" tall while the CX1380RE (Unicel C-7490) are almost 33". Could it be they replaced them with the wrong ones at some point? Would this cause an increase in pressure since I've always noticed this filter runs at 30 psi even with cleaned filters? Any guidance could be a help. I ordered the CX875RE from Amazon and noticed immediately they were shorter than the ones I just cleaned 1 month ago. I can return them but wanted some feedback before I do that and order the others. Thanks in advance!
 

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Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Jun 22, 2014
33,029
Texas, San Antonio/Marion, South-Central Area
Pool Size
17888
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
CircuPool RJ-45 Plus
This is just a hunch, but I suspect the C4520-series filters were replaced with today's C4020 & C5020-series filters. The difference between today's sizes is that the 5020-series is about 6 inches taller as noted HERE. The Hayward site doesn't seem to list archived products, but perhaps a place like Inyopools has some older items in their library that would confirm.
 

Oldpool4629

Member
Feb 8, 2016
18
Dallas, Tx
Thanks for your response. My husband had the filter # written down from our last cleaning just 1 month ago. They are the Unicel C-7490 that are 33". That labeling method just stinks as there is no way to know which one you have. I was just worried that someone prior had maybe put the wrong filters in. I guess if they were that much taller, the thing wouldn't close right.

I've now also posted on another thread because to add to the fun I have a very high stabilizer issue. Long story that I put on the post. I'm afraid I might have to drain the pool a bunch to try and get a hold of the problem. I just can't keep chlorine in the pool. It looks good but I'm afraid of what's lurking unseen o_O
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Jun 22, 2014
33,029
Texas, San Antonio/Marion, South-Central Area
Pool Size
17888
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
CircuPool RJ-45 Plus
Well, good thing is you are in the right place now for help. We'll watch your other thread, but a high CYA means changing some water. But you do it once and never again now that you are using TFP and maintaining your own water. Have a nice weekend. :swim:
 
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