12 feet of Sheer Descents

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For example, this main drain has a wall rating of 88 GPM.

Note: 88 gpm can cause time travel according to the movie "Back to the Future".

I'm not sure if that is a real possibility, but I would not take any chances.

Assuming a total maximum flow of 240 gpm, you would need at least 3 main drains.


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PSPOOL said:
Only need enough projection so it doesn't dribble down the face of the column it will be mounted in (4'x4'x4'.)
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You won't really know how much flow you will want until you turn the pump on and adjust the speed until it performs how you like.

You will probably have different opinions for different people and for different situations like maybe high for a party and lower for a quiet evening by the pool.

In any case, my philosophy is to design it so that you can get the full performance if you want it.

You can always turn it down.

In my opinion, it does not make sense to limit the performance to less than full capacity.

You don't want to spend all of your time and money building this and then being disappointed when it does not perform to your satisfaction.
 
Jimrahbe said:
PS,

You might want to buy several sets of ear protectors.. The kind you use when shooting shotguns... :mrgreen:

Thanks,

Jim R.
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If the sheet stays laminar and intact as it enters the water, the sound is usually not excessive.

However, the guide indicates that a height over 3 feet above the water can result in the sheet breaking up.

So, the 4 foot high sheer will probably break up.

High wind conditions can also cause the sheet to break up.
 
JamesW said:
If the sheet stays laminar and intact as it enters the water, the sound is usually not excessive.

However, the guide indicates that a height over 3 feet above the water can result in the sheet breaking up.

So, the 4 foot high sheer will probably break up.

High wind conditions can also cause the sheet to break up.
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James, you've been a great help and have given me a lot of good information to discuss with my builder. I really appreciate your time and knowledge. Thanks again!
 
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I suspect that the builder will recommend 3" PVC and they will probably say that it will be fine.

If we assume a 3 foot static lift and a 15 foot maximum total suction head loss limit, then that allows up to 12 feet of dynamic head loss.

Assuming a 100 foot total equivalent length, that allows up to 250 GPM for 3" PVC pipe.

So, it will probably work without cavitating.

However, the rule is that the suction should not exceed 6 ft/sec. so the flow rate should be kept below 138 GPM for 3" PVC.

Since the flow will probably be over 138 GPM, the correct size is 4".


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