Never been happy with the degree of filtration..

[Luclin999]

We had a new pump/sand filter system installed about seven years ago when the original equipment (Pump and cartridge) rusted out (the old stuff was over 20 years old).

Had no clue about pools at the time and trusted the pool company for the choice of equipment which I am thinking may have been a mistake.

We have a 17k-18k pool (math seems to place it around 17.5k including spa) and they installed a 1.5hp Pentair WF-26 and a Pentair Triton II TR-100 sand filter.

I have always been unimpressed with the degree of filtration this setup has given us but when I have asked around I have been told "Sand just doesn't do that good of a job" (which in turn made me wonder why they installed it in the first place) but now that I am taking the pool more seriously I started looking into this and am now wondering if the pump may be too powerful for the filter.

Looking up the specs for the two it appears that the TR-100 sand filter is rated for a flow rate of 98 gallons per minute, while the WF-26 pump outputs roughly 135 gallons per minute. Nearly 40% more than the filter is rated for.

Is the additional amount of water running through the filter potentially responsible for the poor filtration results?

 

[mas985]

WF-26 pump outputs roughly 135 gallons per minute. Nearly 40% more than the filter is rated for.

Where did you get that number?

The WF-26 at most would produce about 90 GPM on typical pool plumbing.

 

[Luclin999]

Where did you get that number?

The WF-26 at most would produce about 90 GPM on typical pool plumbing.

I was going off the documentation on the Pentair site which lists the 1.5HP models topping out at 135gmp.

 

[mas985]

That is called the run out point and no pump ever reaches that flow rate on typical pool plumbing. More than likely your flow rate is 80-90 GPM.

But if you want better filtration with a sand filter, you can add a little DE to the filter.

But exactly what is the issue with filtering?

 

[Luclin999]

We have a ~lot~ of pollen/dust that blows around here in Houston Texas and it takes the pump literally days of running non-stop to get the cloudiness down from a heavy pollen week. Honestly, we have never been able to get the water to a completely clear state but part of that may have been due to using the "pool store" method of chemical maintenance.

We changed out the sand two years ago and I just opened it up to wash out the muck about a month ago at the start of the season and didn't see any issues or signs of channeling.

However if as you say, the pump and filter are a good match then perhaps this is just what it is actually capable of.

 

[mas985]

That sounds more like a chemistry problem than a filtering problem. Cloudy pools are most often due to algae. Do you have a good test kit and can you post your results?

Are you following these levels for CYA and FC? http://www.troublefreepool.com/content/128-chlorine-cya-chart-slam-shock

 

[Luclin999]

That sounds more like a chemistry problem than a filtering problem. Cloudy pools are most often due to algae. Do you have a good test kit and can you post your results?

Are you following these levels for CYA and FC? http://www.troublefreepool.com/content/128-chlorine-cya-chart-slam-shock

I am actually SLAMing the pool for the first time right now.

Link

However I will note that even though the pool is still a murky mess that I haven't had to backwash the filter for over 48 hours now (and the pressure hasn't risen by more than maybe one psi during that time.)

With as much organic debris as there is clouding the pool I was expecting to have to backwash the filter a fair bit which is why after two days with no real change to the pressure I was reminded of our past problems and started looking into possible reasons for the (what seems to be) poorer than expected filtration.

 

[mas985]

There are species of algae that are smaller, when dead, than what a clean sand filter can filter out so some DE can help. But the key is to never let algae get a foot hold, so it is never an issue.

 

[Kiss4aFrog]

And when they say you can add a little DE to the filter they aren't talking about much. Typically it only takes 1-2 cups !!

See instructions : http://www.troublefreepool.com/content/133-add-de-to-a-sand-filter

 

[Luclin999]

I tried adding DE a couple of hours ago following the instructions in the link but aside from the initial bump in pressure from adding the DE I haven't seen any other increase so far (been checking about every 30 minutes.)

 

[Luclin999]

Well aside from using the wrong type of DE, I also found out that I was almost certainly using too little, based upon the size of our filter.

Went and got some Cellulose DE substitute and added the recommended amount per the instructions on the package for my filter size (six cups). Hopefully that will improve the filtration a bit.