Filtration requirements for a residential pool

[SethR]

I'm trying to improve the efficiency of my recirculation system by reducing the losses of the plumbing. Specifically, I'm looking at ways to eliminate traditional cartridge/sand filters since they seem to be one of the most restrictive elements in the system.

The CircuPool TJ-16 "Typhoon" Pre-Filter claims that it can effectively remove "96% of all heavier than dirt particulate down to 30 Microns, and 75% down to 20 Microns. Can capture debris as small as 5 microns." Given its effectiveness, can I completely remove the cartridge filter and use this instead?

Is there a hard requirement (based on health/safety I assume) for minimum filtration size of filters? I see that most filters are rated to 20 micron, but I'm not actually sure if this is a requirement and where it comes from. Increasing the filtration size would allow for a far less restrictive system.

 

[Texas Splash]

Seth, welcome to TFP! I have a gut feeling your question is going to generate some interesting replies. But let me just say a few things to start:
1 - Please tell us more about your current pool, equipment, and plumbing. Pics, details, etc are welcome. You should also update your signature with all of you pool and equipment details. See my signature as an example. Knowing what you currently have is a good starting point.
2 - We would ask, why do you think there is a restriction? Do you find return jet pressure low? Filter pressure gauge high? If so, just on occasion, or shortly after cleaning the filter?
3 - While some owners do use a pre-filter, I would not recommend removing your primary filter completely.
4 - The filter's primary job is to capture physical debris only. Health and sanitation is all on the chemistry side which starts with a TF-100 or Taylor K-2006C test kit. Many people underestimate the important of accurate water testing and find water restriction issues are due to excessive organics.

But let's see/hear more about your current set-up and we'll be happy to help.

Also see ------> Pool Care Basics

 

[JoyfulNoise]

The claims made by those pre-filter makers are incredibly biased with no actual proof other than their word ... "we pinky-swear this contraption will remove 99.9999% of the stuff that settles into the bottom of it .... promise ...." While these traps (they are NOT filters, they are traps) work on cyclonic flow principals, it is the density of the particle that has the biggest impact on whether or not it stays in the trap or moves on. If your talking about a piece of inorganic sand that has a density of 3X that of water, then yes, even small particles can be captured. But if the particulate is even close to the density of the fluid it is traveling in, there will be no trapping.

Filtration is important for water clarity. Without a decent filter, your water might be "sanitary" but it will start to get hazy and lose clarity. That is very important from a safety perspective as you need clarity in order to avoid potential injury (crashing into the bottom of a pool, or a wall, or another bather). Suspended solids will also become substrates for bacteria and algae to grow on. Filtration and removal of those potential substrates is equally as I important as sanitizer levels.

 

[DavidLast]

Specifically, I'm looking at ways to eliminate traditional cartridge/sand filters since they seem to be one of the most restrictive elements in the system.

May I ask why you are saying this? What is the basis for this statement? Is it because it collects dirt and increases the pressure or are you meaning some other way?

The CircuPool TJ-16 "Typhoon" Pre-Filter claims that it can effectively remove "96% of all heavier than dirt particulate down to 30 Microns, and 75% down to 20 Microns. Can capture debris as small as 5 microns." Given its effectiveness, can I completely remove the cartridge filter and use this instead?

We tested some of these on a commercial water body with very high bathing loads and found they collected nothing. If the water is filtered and clean our experience was they were not worthwhile in the setting we tested in. Anecdotally I hear some people have seen some benefit, however, it is a whisper rather than a firm statement.

 

[DavidLast]

Is there a hard requirement (based on health/safety I assume) for minimum filtration size of filters? I see that most filters are rated to 20 micron, but I'm not actually sure if this is a requirement and where it comes from. Increasing the filtration size would allow for a far less restrictive system.

There is no hard and fast rule I am aware of or have come across in the various statutory documents I have read. The usual specification for filters in health compliance documents for public facilities is based on flow rate over area.

 

[SethR]

May I ask why you are saying this? What is the basis for this statement? Is it because it collects dirt and increases the pressure or are you meaning some other way?

We tested some of these on a commercial water body with very high bathing loads and found they collected nothing. If the water is filtered and clean our experience was they were not worthwhile in the setting we tested in. Anecdotally I hear some people have seen some benefit, however, it is a whisper rather than a firm statement.

I'm just interested in looking into creative ways to reduce the head loss (without compromising safety/sanitation) in the system and as a result, energy consumption

 

[PoolStored]

I'm just interested in looking into creative ways to reduce the head loss (without compromising safety/sanitation) in the system and as a result, energy consumption

If your goal is to reduce energy consumption, install a Variable Speed Pump (VSP) and run on low rpm. Most around here run 11-1600RPM with VSP and use about 150-200 watts...a light bulb of energy. Runs me about $20/month to run my pump...

 

[Jimrahbe]

I'm just interested in looking into creative ways to reduce the head loss (without compromising safety/sanitation) in the system and as a result, energy consumption

Seth,

I have to assume you already have a VS pump.. If not, that is the only thing that will reduce your energy consumption, in any noticeable way..

I have a 3 HP IntelliFlo that runs 24/7, mostly at 1200 RPM, for less than $20 bucks a month.. My pump is about 10 years old.. Newer pumps are much more energy efficient, and they would probably cost me less than $10 bucks a month.

Thanks,

Jim R.

 

[JamesW]

I'm just interested in looking into creative ways to reduce the head loss (without compromising safety/sanitation) in the system and as a result, energy consumption

What flow do you want or need?

What are your current head loss calculations for the flow rates?

For a residential system the flow will rarely need to be higher than 40 GPM and most of the time, you can go a lot lower.

At lower flow rates, the cost to operate is negligible.

 

[mas985]

I'm trying to improve the efficiency of my recirculation system by reducing the losses of the plumbing. Specifically, I'm looking at ways to eliminate traditional cartridge/sand filters since they seem to be one of the most restrictive elements in the system.

Cartridge filters have the least head loss of any of the filters mainly because they do not have multi-port valves which have a lot of head loss.

Is there a hard requirement (based on health/safety I assume) for minimum filtration size of filters? I see that most filters are rated to 20 micron, but I'm not actually sure if this is a requirement and where it comes from. Increasing the filtration size would allow for a far less restrictive system.

Not for residential pools. In general, DE filters can filter the smallest debris (5 microns), then comes cartridges (~10 microns) and finally sand filters (~20 microns)..

- The particle size that can be filtered really doesn't improve water quality that much because most people can't see objects that small anyway. Visual acuity limits resolution to around 0.017 degrees. So to be able to see a 20 micron particle requires it be less than an 2.7" away from your eye which would be out of focus.

- Sanitation of the water is accomplished by chlorine, not the filter. The filter is just there to remove debris which is more for aesthetic reasons than anything else.

 

[DavidLast]

I'm just interested in looking into creative ways to reduce the head loss (without compromising safety/sanitation) in the system and as a result, energy consumption

As the question is specific to filtering, I am assuming you are interested in reducing pressure drop across the filter.

In a way this doesnt make sense. Over time a sieve will block and let less and less water flow through and likely assuming it is open will eventually overflow. To overcome this increasing the pressure over the sieve will result in more water passing through even though partially blocked etc. This is effectively how a filter works. So to reduce energy and pressure drop across the media (sieve) it would be conceivable to clean the filter on a fixed and rigorous schedule. Perhaps not practical and eventually destined to require media change at some future point as the media becomes rounded, blocked or simply worn out.

Another option could be to slow the flow rate across the filter. For sand the slowest filter practical rate would likely be about 10m3/m2/hr. Backwash rate would still need to align with manufacturers requirements. For cartridge slowing the rate down is potentially possible. However I have no information other than practical on slowing this to give an exact lowest possible flow. It isnt really feasible to slow D.E. by very much outside manufacturers design point so wouldn't be something to try.

However, and this is a big however, the cost for the larger filter is likely to be so high it is not justified by the energy cost saving. An alternative way could be use of a VSD pump as has been mentioned by others. Effectively, if this is your inclination, it would be possible to calculate the speed/flow based on manufacturers data against the filter data and arrive at a nominal operational point where the filter flow rate is significantly slowed and the pressure reduced as a result.

 

[Bperry]

I'm trying to improve the efficiency of my recirculation system by reducing the losses of the plumbing. Specifically, I'm looking at ways to eliminate traditional cartridge/sand filters since they seem to be one of the most restrictive elements in the system.

The CircuPool TJ-16 "Typhoon" Pre-Filter claims that it can effectively remove "96% of all heavier than dirt particulate down to 30 Microns, and 75% down to 20 Microns. Can capture debris as small as 5 microns." Given its effectiveness, can I completely remove the cartridge filter and use this instead?

Is there a hard requirement (based on health/safety I assume) for minimum filtration size of filters? I see that most filters are rated to 20 micron, but I'm not actually sure if this is a requirement and where it comes from. Increasing the filtration size would allow for a far less restrictive system.

In case it wasn’t obvious, all the folks above me are saying that using a variable speed pump running on low speed will save you some money but keeping the same single speed pump and removing the filter isn’t going to save you anything and is a bad idea for other reasons as well.