Are cartridge filters directional ?


Gold Supporter
Mar 21, 2016
Marrietta Ga
I have had this for almost 5 years and have replaced the cartridges several times but have never noticed the word " bottom" on one side until today. Does it matter?


TFP Expert
Platinum Supporter
May 23, 2015
Tucson, AZ
Yes. Sending the water flow the wrong way will rupture the cartridge. This is why cartridge filters can not be backwashed.

Misunderstood the question.

I have not noticed that. Is there a difference in the upper and lower manifold diameters?


TFP Expert
LifeTime Supporter
In The Industry
Jun 12, 2009
NW Ohio
Not always, but if it is labeled then that means the top and bottom gaskets are molded differently. I don't think it usually makes much of a difference, but if you put it in upside down you could make a less good seal and reduce the efficiency of the filter.

Bama Rambler

Mod Squad
TFP Expert
Bronze Supporter
LifeTime Supporter
Jun 22, 2009
SouthWest Alabama
If it's written on my PWWCT200 Pleatco filter I've never noticed it, and there's nearly 100% chance I've put them in upside down. I have never noticed a difference.

I'll be looking at them in the next couple of days now though. :)
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