Multiple filters?

I have been reading about the different types of filters, (sand, DE, Cartridge) I like the idea of the easiness of the sand filter, but like the idea of Cartridge filter. I was wondering about using both. I have found some post that pose the question, however there was no answer. I have seen the suggestion of both connecting them in series and parallel, switching between the two. I have read about using DE in the sand filter, however that would mean involvement on every backwash. Being an automation engineer, I would like to automate the backwash and not have to worry about it.

Bob

There really is no point to having multiple filters. When sizes properly, you only need one filter. If you get a large enough cartridge filter, you will only have to clean it once a year and will trap more dirt than the sand filter so really the sand filter would be pointless. If you put DE in the sand filter, it will probably equal the cartridge filter in trapping dirt so the cartridge becomes pointless.

The choice in filter is really what you want to deal with. Personally, I like the cartridge since it filters well and I only have to clean it once a year. Plus back-washing would mean replacing CYA and salt for the SWG much more than I do now.

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Originally Posted by bobmcj

Being an automation engineer, I would like to automate the backwash and not have to worry about it.

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OK, I'm grinning, big time. :D :rolleyes:

You have two options, in automating pool gear:

1. You can use pool industry valving, controls, and actuators, in which case automation is the REASON why you'll have to worry about it.
2. You can use full industrial piping and controls, in which case your automation may well cost more than your pool does.

I've worked with large commercial pools for years, and I pretty much stopped trying to use automation -- of any kind more sophisticated than a time clock -- 20 years ago. Pools NEED to be observed with a Mark I eyeball, a Mark II olfactory sensor system, and a Mark III aural input device on a regular basis.

I could automate most of what I can tell by glancing at the pool, as I walk downwind of it, on the way to check and listen to the system. But to RELIABLY do so, and to gain input that provided 90% of the info and problem detection I gain from my walk by would require all of the following:

1. RPM sensing on the motor shaft
2. Vibration sensing on the motor
3. Digital read out of both influent (< atm) and effluent (> atm) pressures
4. Volt-amp digital read out
5. Digital flow rate read out
6. Smart analysis system that could detect cavitation, prime loss, low rate suction leaks, etc. from values detected in 1 - 5.
. . . and that's just to monitor the pump and flow!

You'd know better than I, but my guess such a system -- at 99% effective availability -- would cost over $5,000. But, I have my doubts you could get it for that: most of the people I've encountered trying write pool monitoring and control software, understand hardly anything about pools.

So, if you are pursuing this as a means to gain genuine efficiency, fugeddiboutit!

However, if you are a tinkerer at heart, and want to do this as a hobby, I'd recommend this site,
Swimming pool control with Linux as an example of what can be done.

In some ways you are correct, there is an added cost for sensors, pressure, flow and amps. No need for any read outs. Everything would be displayed at a PC. The PC is only used for displaying data and storing historical data (trends). I do not know why anyone would want to use the PC (linux or windows) for actual control, they are not made for that type of control. I would use a PLC (programmable logic controller).

I’ve designed/written code for large Ultra Pure Water systems which is basically the same…just a lot more equipment and processes.

What it comes down to is that I am a nut and really enjoy this kind of stuff. Yes it may be over kill, but hey, is BIGGER ALWAYS BETTER!!! I think I could easily do it for less than $5,000. On the other hand, if I ever sell the house, would anyone have a clue how to use it?

Who knows, I may or may not add automation to the pool. I have been looking at some of the off the shelf stuff, like the Pro Logic from Hayward or the Intelli stuff from Pentair. Although I am a little worried that it is like most home automation stuff….cheaply made, overpriced, and nonadjustable.

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Originally Posted by bobmcj

I do not know why anyone would want to use the PC (linux or windows) for actual control, they are not made for that type of control.

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I do not know why anyone would use a PLC for a home pool; they are not needed for that! ;)

Actually there is an application for a PLC in *commercial* pool ops, managing a bleach & acid feed system, a bleach chiller, and ORP & pH electrode inputs. Conventional ORP / pH controllers don't do well on pools, because it's too hard to keep them from over-controlling, and because the relationship between ORP electrode mV output and free chlorine levels is highly variable. I worked on developing a system using a chem feed system I'd developed, that had a consistent service life, allowing manageable PM intervals.

I was trying to couple it with a control system that had inputs from ambient temps, ORP, pH and some other things. By properly locating the feed inlets in relation to the probes, you could BOTH clean the probes AND use them for chem feed proving. If I'd been able to finish and market it, it would have dramatically reduced operational costs and increased pool water quality for small commercial pools that don't have a dedicated pool staff. Now, the cost benefits would not be so great, since SWCG provide an increasingly viable alternative.

Nothing's ever been marketed however, with a control concept that is as simple and comprehensive, and self-alarming. But, I didn't have the money to market the product or the time to develop the programming expertise needed. (Still have a couple of working PLC's though!)

I did learn how to use $80 time clocks, and predictive dosing, to outperform $5,000 pH/ORP controllers!