Help with pump sizing / flow rate

[A_kraker99]

This will be the third season I have had my pool. I am pretty sure the package I bought was a terrible match between filter size and pump size. I am pretty certain the pump is way over-powered for the filter and may be causing channeling because last year my filtering was pretty poor. Can someone help me find the flow rate of my pump and let me know what I should change?

15x30 12,000 gallon pool

Pump: Waterway ecco sd-15-1n11c 12 amp 1.5HP

Filter: ecco 22" diameter 55gpm max flow rate, 35 PSI max working pressure, 250 pounds of sand

 

[mas985]

Where the pump and filter sold together or purchased separately.

What is the clean filter running pressure?

Typically, that pump would produce less than 55 GPM on AG plumbing.

But why do you think the filtering was poor? What were you seeing?

 

[A_kraker99]

One of the problems is that the running pressure never seemed to change. I could go 4-5 weeks and not even tell a difference. My pressure gauge is broke right now but I will let you know when I get a replacement.
What is AG plumbing?

Last year all my levels were kept in check but it was constantly cloudy no matter what I did. The only way to clear it up for a while was to put clarifier in. I was up to running the pump 12 hours per day for a while. Still didn't help.

 

[mas985]

AG = Above Ground

Last year all my levels were kept in check but it was constantly cloudy no matter what I did.

That usually points to bad chemistry. However, sand filters don't filter smaller particles as well as DE or cartridge and if you have a lot of dead algae, it may just recirculate it. Next time you have the same issue, try a little DE in the sand filter. That can help remove the remaining small particles.

 

[A_kraker99]

Could be. I did have one algae outbreak before all that happened. Sand really can't filter that? Even after doing clarifier?
Any idea why my filter pressure never went up even after several weeks without flushing?
Also. What would you estimate my flow rate? I thought 1.5HP pumps were doing around 100 GPM
http://www.hwpinc.com/parts/pumps-ww/spaflo-performance.jpg

 

[A_kraker99]

I should mention that I use a Taylor test kit and I'm pretty picky about water chemistry so I don't think it was off at all. Just suspended dead algae or something. When I got algae it was just growing In The bottom of the pool and nowhere else. chlorine levels were around 5-6 at 40 CYA so I'm not sure what happened there.

 

[mas985]

When I got algae it was just growing In The bottom of the pool and nowhere else.

So did you perform a SLAM to get ride of it and was the cloudiness right after you killed off the algae?

 

[A_kraker99]

Yes. Did a SLAM. cloudiness seemed to go away initially but came back. Details are fuzzy now. I kept having to vaccum what appeared to be dead algae off the bottom of the pool but it kept coming back.

 

[mas985]

It was probably passing through the filter. Not uncommon for sand. A little de usually clears it up.

 

[A_kraker99]

How much DE can I add?

Also, what's the recommended sand replacement interval on here? I have been manually cleaning every year using the hose in the sand trick. Wondering if I would benefit from replacing with something like this. ZeoSand Alternative Pool Sand Filter Media - 50 Pounds https://www.amazon.com/dp/B00EZB2K3A/ref=cm_sw_r_cp_api_VSXizb1NFB8CW

 

[mas985]

Between 1-2 PSI rise.

As for sand replacement, in most cases, that should not be necessary.

 

[A_kraker99]

So no truth in the theory that the sand wears down over time and needs to be replaced?

 

[mas985]

Over millions of years, yes. But not over the lifetime of a filter.

Does Sand Wear Down??

 

[A_kraker99]

Thanks for the link. I guess I probably heard it from someone who sells sand.

FYI. I'm running at about 12 PSI right now. Sound about right?
What is that actually measuring? PSI of the inlet before filtering?

 

[mas985]

PSI of the inlet before filtering?

Yes. It is a reflection of the amount of head loss from that point forward. And sounds about right.

 

[A_kraker99]

What kind of pressure would I see if the filter was channeling?

 

[mas985]

It isn't about pressure but flow rate through the filter. Most manufactures put a maximum flow rate of 20 GPM/sqft but many pools operate above that without channeling. If you want to test if your filter is channeling, throw some DE (or fine dirt) in the skimmer and see if it comes out of the returns. If it doesn't then it is likely be be dead algae that made it through which from other's experience, is normal.