What is the best way to determine the ideal pump run time?

[JasonLion]

What is the best way to determine the ideal pump run time? For that matter, what is the criteria for determining the ideal run time?

I know of two approaches, both of which have some problems. The first is to guesstimate your flow rate and then aim for one turnover. The second is to experiment with different run times, examining water quality carefully to see how short the run time can be without impacting water clarity significantly. These two approaches imply different criteria, either one turnover, or water clarity, are the most important factor.

The aim for one turnover approach can be problematic because it requires a fair bit of knowledge to make a plausible guess at the flow rate. The experiment based on water appearance approach takes weeks, or months, requires some practice at judging water clarity, and can be thrown off by unexpected events that impact clarity (major rain storm, swim party, etc).

As a result of the problems with the two common approaches, we often resort to saying something overly simplistic like, try 12 hours, which works well enough a good portion of the time, but is hardly optimal.

As energy costs continue to increase, finding a minimal acceptable run time becomes more important. Is there some way we can simplify that process for people?

 

[257WbyMag]

I think that most of the average pool owners here, myself included, would probably find it easier to simply judge water clarity and test results to determine what works best. An arbitrary starting point such as 8 hours or 12 hours is a good place to begin. Then one can simply back off the run time, test for the presence of excess CC at regular intervals, and actually judge how the water "looks" to determine what seems best.

After making an earlier posting on a related thread about this very topic which indicated that I run the pump 4 hours a day plus the time that swimmers are in the water, I do realize that the 4 hours for me is not always a hard and fast rule. As you mentioned, there are times when it may need to be increased in the event of environmental factors that come in to play. Rain, rain with lots of dust, and bad pollen days can make running the pump longer a necessity.

I don't possess the experience or tools to really determine how many GPH I am filtering. I have a guess, but I don't really know how accurate it is. But this is where test results, look, and feel all factor in. It may be subjective for the most part but I cannot think of a better way to judge it.

 

[Durk]

I have had my 'new' pool since 2004 and have gone through the reduce time approach and I ended up at 4 hours after 4 years (12, 8, 6 and 4 last year). My test criterion is the water appearance at pool floodlight at night. The concentration of visible particles within the beam should be very low and they should be extremely fine. This is as good as it gets with 24 hour circulation. I have an oversized 60-ft DE filter with 1.5 hp pump on 28000 gallons and no spa or water features and all 2" plumbing (including filter insides). I run two hours in the AM to clean surface with the skimmers and two hours in the evening to distribute chemicals and I wouldn't want to reduce either of those.

I will run it 24 hours in a real good rain storm until back to clear, but I had to do that when I was running 12 hour cycles the first year. The 12 hours was recommended by the PB (Anthony & Sylvan) but that is 'clearly' overkill.

I recently ran the numbers for the dynamic head calculation. I came up with 4 hours for one turnover. For those with pool lights, I recommend this approach to judging clarity--daytime 'looks' really just give you a sense of clear or not clear. At night, you get degrees of clear.