Hayward DE7220 integration with Hayward ECOSTAR SP3400VSP; minimum RPM requirements

[PoolDoc]

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[ Hmm-mh. Mark and I cross posted. He's being more patient about this than I am. ]

You are seriously over-thinking this.

Your assumption that that there is a precise optimal point of operation for your pool and all the equipment is incorrect. Pursuing that mythical optimal point will consume a great deal of time and effort, with very little benefit.

The BBB approach to pool chemistry and operation is strictly a "good-enough" approach; I've long referred to the pursuit of optimal chemistry as "chasing the numbers". That could just as well refer to your request.

In theory, one could describe a rational basis for optimizing pool operation in the manner you are seeking; in practice, there are too many uncertainties to do so in a genuinely meaningful way.

Just to take one example: you want to know "optimum" flow rates for your DE filter. But, you don't say optimum to what end. Minimum energy use? Maximum filter cycle life? Minimum DE consumption? Maximum water clarity? Or something else?

=> Precisely determining the minimum energy use would require an engineering study of the non-linear relation between watts consumed and gallons moved for your pump; hydraulic analysis of your unique piping arrangement, including any on/off cycles of your solar system, and a field study of actual dirt loads on the water in your pool. Incidentally, most of the West Coast pool solar heating systems I've seen are energy pigs, due to the great increase in pump effluent pressure required to circulate water through a sub-optimally designed solar loop.

=> Maximum filter cycle runs would, among other things, require arranging your system so the pump was never shut off during a run: few DE filters can redistribute the DE "optimally" after the initial pre-coat!

And so on . . .

[rogue]

Hi,

Ben thanks for the perspective. As a mechanical engineer I understand your comments. That said my intent is to determine if there is a "go no lower than" flow level for the filter. My guess is the final RPM setting on the new ECOSTAR will be between that point and the 55 GPM RPM setting for the solar array. My goal is to minimize energy usage

Perhaps the minimum filter flow rate is simply achieved by observing that the filter tank is full and water is coming out of the air bleed port at the pressure gauge?

Mark, I am planning on replacing the current Super II one HP motor "SP 3010 EEA2" with the ECOSTAR SP 3400VSP. The data points you requested are:

1. I understand "pre-coat pressure" means the filter pressure just AFTER the new DE has been applied. In my case this is 14 PSI without the solar valve open and 20 psi with the solar valve open for my current system with the Super II pump
2. It looks like there is one main drain line coming into the skimmer from which the single 2 inch suction line goes to the pump. FYI it is 25 ft from the skimmer to the Super II pump inlet. My guess is that there is one 45 deg bend and two 90 deg bends up to the pump inlet
3. It is 56 inches from the filter pressure gauge to pool water level.

Looking forward to any advice you can provide on a reasonable flow/ speed 1 rpm setting for the new ecostar when the solar array is not engaged. Since energy conservation is the goal, perhaps there is a rule of thumb re length of pump operation at lower RPM vs shorter pump operation time at higher RPM?

[mas985]

Perhaps you missed my second post:

There is no minimum flow rate and given the size of the filter, you will never reach the maximum flow rate so the filter is not even an issue here.

If you want the most energy efficient (gallons/watt-hr) setting for the EcoStar, that would be around 1000 RPM. You would just need to set the run time long enough to clean your pool.

Start with 6 hours and see how that works.

[rogue]

Looks like we had crossing posts. Appreciate the prompt responses!

The ECOSTAR 1000 RPM data point you provided is what I needed along with perspective re the filter.

My impression is that I will need to install a flow meter to get the GPM for the 1000 rpm in order to determine run time. Looks like the Blue White F30200 PR will work. I don't have much straight pipe after the filter but do have a 30 inch clear pipe run between the pump outlet and the filter.

Will the flow rate seen on the gauge mounted before the filter be much different than the reading if it is mounted after the filter?

Regards,

Chris

[mas985]

My impression is that I will need to install a flow meter to get the GPM for the 1000 rpm in order to determine run time

Flow rate has little to do with pump run time. I know that you read on the internet that a pool needs so many turnovers per day but it is somewhat of a myth. There are pools that need a couple of turnovers a day while there are others, like mine, that can get away with less than a 1/2 turnover per day. So knowing the flow rate is not really that important.

There are two main factors for run time:

Chlorine - This most important. If you have an SWG, you need to run long enough to get enough chlorine in the pool. If you manually dose, then you need to run long enough to circulate the chlorine after adding. 30 minutes is usually enough. But either way, you need to keep the FC levels per Ben's best guess chart.

Cosmetics - This is mainly personal preference. So if you don't care that your pool has a little dirt on the bottom or floating on the top, then you can get away with less run time. However, if you are pretty anal about having a pristine pool, you will need a lot of run time. But this is purely subjective and totally up to you. There is no right answer. Splitting up the run time can also help keep things cleaner without increasing the run time.

So run time should be based only on these two factors. Most pools with single speed pumps don't need more than 4 hours of run time. However, you may need a little more when running on lower speeds which is why I suggested 6 hours. But if you are already running more than 4 hours for solar, then I doubt you need any additional run time.

[rogue]

Using Natural Chemistry's Pool Perfect plus PhosFree, emptying the skimmer once per week, and breaking down/cleaning the DE filter twice per year I've kept phosphates near zero with no algea issues in the past 8 years. In the San Diego swimming season Apr -Oct I remove leaves and debris while swimming and use the Polaris 280 once per month or so for dirt. The chlorine generator easily maintain proper levels at 40% for 7 hours run time currently. Given your comments 6 hrs/day from 11-5 should work and will primarily be at solar heat speed resulting in an 80% pool water turnover during the swimming season. I can monitor the chlorine generation percent and adjust if the shorter run time impacts required chlorine levels.

During the winter season Nov-Mar solar would not be engaged. Based on your comments the 1000 rpm rule should work for the 6 hrs. Even so I will likely have to decrease the chlorine generation level.

During Dec through Feb pool temp drops below 55...do I even need to run the ECOSTAR and filter at these cold temps? I note that the Chlorine Generator drops off the line when it gets this cold!

[BigDave]

Please note, the EcoStar's built-in timers are inoperative when the pump is in relay mode.
A flowmeter before the filter will be exposed to the dirt the filter removes likely interfering with the operation of the meter.

[mas985]

During Dec through Feb pool temp drops below 55...do I even need to run the ECOSTAR and filter at these cold temps? I note that the Chlorine Generator drops off the line when it gets this cold!

I have about the same situation. When the water temp gets below 50F, my SWG stops running so I will usually just shut off the pump. I once went 2 months without running the pump and near the end as the water started to warm, the water had a ting of green color. So you can go without running a pump but you need to keep an eye on the water and if starts to turn green or cloudy, you may need to add some chlorine manually.