Expected FC Drop

[scader]

I'm currently slamming the pool after a bit of algae formed, had FC at 20 at sunrise, CYA is 50, pump/salt gen is turned off. After a full day of sun the FC is at 19 (CC effectively 0). I know slamming is about what happens overnight, but wouldn't you expect FC to drop more than 1ppm in a full day? ...the CYA isn't that high. Not a big deal, just curious.

 

[mknauss]

Hard to say. Could be some testing error, etc.

Continue until you pass the three criteria as described in SLAM Process

 

[proavia]

pump/salt gen is turned off

Your pump needs to be on during the SLAM Process

 

[scader]

I was curious if the algae would drop so I could vacuum to waste, but I can turn it back on. Does it matter the speed? I typically run it at 1100rpm 24/7. (A flow guage is a goal for next year.)

 

[proavia]

You need the pump running to mix the water and allow the filter to filter out the dead algae.
1100 rpm should be fine. You may wish to increase the speed to hasten the process.

No real need for a flow gauge. You can set the rpm to whatever you need to accomplish the task at hand.

Keep an eye on the filter pressure and baxkwash when the filter pressure increases 25% above the clean filter pressure.

 

[Newdude]

(A flow guage is a goal for next year.)

Why ? You already have a measurement with RPMs. Whether we call it 60 MPH or 95.6 KPH, or 88 feet per second, it's going as fast as it's going and they all mean the same thing.

 

[scader]

To determine if I have to run it 24/7 to do a complete turn over. Not directly related to this thread, but I assume even at 1100 that would happen in less than 24hrs for 30k gal.

 

[scader]

Silly question: I turn the pressure gauge markings so that Start is the initial reading after a good backwash, right? That seems to be 20 psi.

 

[Newdude]

To determine if I have to run it 24/7 to do a complete turn over

Why ? You need the filtering that you need. In the spring and fall it's alot more and in the mid season its next to none with very little debris blowing in. Turnover(s) doesn't accurately reflect what's going on around the pool at that point in the season. It's a useless stat.

*as a side note, I personally believe the effects of mixing make the turnover stats miss by a mile.

 

[scader]

I was of the understanding that pool owners attempt to run the pump only as need to circulate once over for cost savings. That would vary based on conditions, are you suggesting to run it based on visual debris? I have my pump scheduled to run 1100 23.5 hrs and at 3100 for a half hour in the late morning to pull in debris, stir things up, and a salt gen boost (if that) before swimmers.

What do you mean by the effects of mixing? Keeping the water circulated?

 

[Newdude]

I was of the understanding that pool owners attempt to run the pump only as need to circulate once over for cost savings

Who says it needs to be circulated once ? You might need .2 turnovers in July, and 3 turnovers in May. One turnover (or 2 or 3) doesn't account for what's going on at that point in the season.

Imagine you and your neighbor have a row of trees between you and the wind decidedly blows your way. You need considerably more filtration than them. And you live next door. Imagine the guy down the road or across the country. Assigning a set rule is a joke.

I have my pump scheduled to run 1100 23.5 hrs and at 3100 for a half hour in the late morning to pull in debris

So you're choosing to filter and skim around the clock and will likely never need more volume moved. It's awesome and many of us do for peanuts with a VS pump. But if you get over run with pollen in the spring, you need more volume through the filter than you had, not an arbitrary # of turnovers. Bumping your RPMs will increase the flow the same way that going from 20 GPH to 25 GPH will. Ironically, to increase the flow meter results, you'll do so with RPM. Skip the middleman.

Today is windy and there's lots of debris, tomorrow is still and there is next to none. Turnover doesn't even work day to day, much less across the season.

What do you mean by the effects of mixing? Keeping the water circulated?

When the water is circulating, some already filtered water makes several trips while some stays in the pool. The industry reccomends 3X turnovers because the hydraulics charts say most of the water will have gone through the filter by then, and that's the part I don't believe is accurate in the real world.

Turnover of Pool Water - Further Reading

www.troublefreepool.com

and a salt gen boost (if that) before swimmers.

SWGs are to replace the daily FC loss from UV. When managed properly, swimming shouldn't appreciably affect anything, unless it's a blowout party.

 

[scader]

Thanks for the link and thoughts, appreciate your time to respond. Interesting... I've always set my swg to whatever strength needed to maintain FC with it continually running at a low speed (currently about 45% output). I suppose I could run it at max strength and run the pump less., but it sounds like the full time, low volume speed is a valid approach.

 

[Newdude]

but it sounds like the full time, low volume speed is a valid approach.

It's a few less things to fiddle with.

My pump draws the same energy 24/7 on low RPM as 2pointsomething hours on high speed. I'd need 4 to 6 hours to skim/filter, maybe more, and 12+ hours for the SWG. It's far cheaper to just run it around the clock low and be covered across the board.

For those with higher flow requirements (heater / cleaner / waterfalls / etc) they just bump it when needed for those things, then revert to slow and cheap.