# Thread: Question on pump run time and pool size

1. ## Question on pump run time and pool size

Good morning, I was referred here by a friend and have been reading up on pool care here for about a year and have a couple of questions. As background my wife and I bought a house about 18 months ago with an approximately 33,000 gal inground pool. This is my first experience with pool ownership and it has been a challenge, although we do have a couple of pool stores nearby who seem to be compentent and honest although not inexpensive. They helped us close after moving in and we used them for testing and chemicals last season. My intention is to take control of this thing myself and minimise the cost and work as much as possible. Unfortunately the pool was in worse shape than we thought and as a result last summer we just about re-did the entire thing, new steps, liner, pump, resurfaced the concrete and replaced the fence. I am planning to go to BBB using the liquidator. I want to add a timer to the pump, and wonder how long I should set the daily runtimes, at least to start with. Also I would like to calculate the pool size more accurately(for use with the pool calculator on this site). Could that be done by adding a chemical or salt, If I decide to add salt, and testing for the change in PPM? Any thoughts would be appreciated.

2. The ideal pump run time depends on the relative sizes of the pump/filter and the pool, the water temperature, and bather load. There is some math you can do to get a starting estimate, but often it is simpler to just try 12 hours a day, see what happens, and adjust as needed from there. Wait a week after changing the pump run time before evaluating the water and keep in mind that you will need more run time was the water warms up.

Adding salt is a reasonable time to try and estimate the pool volume based on the observed change in salt level. Get a salt reading before adding salt and again after adding salt and then play with the calculator to see what size pool would have the observed change in salt level. The initial salt reading is very important, since pools almost always have a significant starting salt level. Keep in mind that the better salt tests are +-200 ppm, so you are really only going to be able to calculate your pool size to within about 10%.

The approach of estimating pool size based on chemical measurements is never all that accurate because the tests aren't really that accurate. The FAS-DPD chlorine test can measure down to 0.2, which is probably the most accurate test, perhaps 1 part in 100 when raising FC by 20. But chlorine can easily be lost to other factors, even at night with no algae, and chlorine decays over time so the potency of the source is always open to some question, so a FC test would only be a little better than the salt test at best. PH is affected by too many factors to calculate accurately, and the other tests are significantly less accurate.

3. There is a way to accurately determine pool size by chemical testing of the water but it is not easy, requires a good test kit such as a TF100, Taylor K-2006 or BETTER and takes a bit of time. I refer you
here,
here,
and here.
If you undertand these documents then you can do it.

4. ## Pump rn time and pool size

Thanks very much to both of you. If I can just convince the wife the pump does'nt need to run 24/7 I will try twelve hrs an go from there. I think I do follow the calculations you referred me to, I will play around with it and see what I get. I am sure to have more questions as I get into this, I must say this is one of the most helpfull and pleasant forums I have seen.

Thanks again

5. Hey, Mark, and welcome to TFP

We sure do have some really smart people here and they are always willing to help!

6. ## Re: Question on pump run time and pool size

mstan

Welcome aboard. I see you have a few questions already answered. This is what makes this forum so great. We have many folks can help answer most any questions. I have been here for about 3 months and my pool water is well balanced and ready for swimming. It took about a month to learn the terminology and how one things effect another. After you do some more reading I'm sure you will have it down pat.

The one thing that I have learned that I feel is the most important is not to get excited if your readings are off a little. Pool water changes at it is used as well as when it warms up. After you get the water balanced to what it should be testing every weekly will give you confidence you are doing it correctly.

Good test kit and develope a spread sheet so you can see how things are changing. My SWG pool has used up muratic acid (8oz -1cup) a week keep my pool happy. I also bought pool clarifier that makes the particles in the pool heavier and group together and stay in the filter.
Bottom line enjoy your pool and don't let it get you all woundup.

7. ## thanks for the welcome

Thanks, there is an amazing amount of knowledge here, much of which is probably over my head. However I feel much less stressed at this point, but I do want to be sure to take the best care I can of my larger than expected investment. It would appear the previous owner was a total idiot. From what my neighbor, also a pool owner says, he just kept adding chlorine until the water was clear, never mind the levels or the PH. Thanks to you guys I hope to actually enjoy the pool this summer.

8. ## Re: thanks for the welcome

Originally Posted by mstan
Thanks, there is an amazing amount of knowledge here, much of which is probably over my head. However I feel much less stressed at this point, but I do want to be sure to take the best care I can of my larger than expected investment. It would appear the previous owner was a total idiot. From what my neighbor, also a pool owner says, he just kept adding chlorine until the water was clear, never mind the levels or the PH. Thanks to you guys I hope to actually enjoy the pool this summer.

I figure if you have a good test kit you should have everything balance before swimming season.
Clean the filters and or backwashing is also a critical step in the spring after all the pollan falls from the trees.
We don't have trees in Arizona. Only cactus and rattlers... LOL
It sure is tuff getting the rattlers out of the pool so we can swim thou.
But they sure taste good deep fried.

Iggy in the cool part of Arizona

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