Bog plumbing (pool to pond)

[sherry]

Hello, I have a 28'x15' (used-to-be swimming) pool about 400 sqft and has 12000 gallons. The pool pump is intellipro variable speed with 3600~7500GPH, with 2'' inlet and outlet. The current plumbing is 1.5'' skimmer + 1.5'' bottom drain -> (2'') pump -> cartridge filter -> chlorine generator -> pool return. I plan to build a 8'x10'x2' pea gravel bog on the pool deck. Water overflow back to the pool.

1. If I re-use the pool's pump, I plan to direct part of them to the bog and the rest to the pool return jets. There is 100ft distance from the pump to the bog, would this be a problem? I plan to adapt the 2'' to 3'' and run 3'' flex PVC for 100ft. Then adapt to 2'' and run to the bottom of the pea gravel bog.

2. Another way is to add a new (self priming) pump (about 8500GPH), I'll run a 3'' flex PVC from water to the bog. I'm not clear on how to do the plumbing. Do I need to pre-filter the water using a new skimmer (as I can not access the pool skimmer)? Do I just place the inlet pipe in the middle of the water?

3. which way is better, (as in 1) replumbing the pool pump, half go to the bog and half go to the pool return, or (as in 2) keep the pool pump for recirculation only and add a new pump to pump the water to the bog.

Thank you!

 

[GBBUDD]

changing a 2 inch pipe to a 3 inch really won't increase volume without adding high pressure. A step from 2 inch to 3 inch is a lot more than you may think. 2" is good for 4500 gph a 3 inch if i remember correctly is over 13000. you can't push a round peg through a square hole without serious increase in pressure. and in this circumstance i doubt its possible.

two smaller pumps to push what a larger pump will uses less energy.

and if you have two pumps if one fails there's another already going to keep things alive

 

[sherry]

changing a 2 inch pipe to a 3 inch really won't increase volume without adding high pressure. A step from 2 inch to 3 inch is a lot more than you may think. 2" is good for 4500 gph a 3 inch if i remember correctly is over 13000. you can't push a round peg through a square hole without serious increase in pressure. and in this circumstance i doubt its possible.

two smaller pumps to push what a larger pump will uses less energy.

and if you have two pumps if one fails there's another already going to keep things alive

Thank you! Is it recommended that I keep using 2'' PVC for all the plumbing and using pool pump for recirculation and then a new pump (4500 gph) for the bog (as in 2)? Could you please advise how to pre-filter the water (if it's needed) before the new pump?

 

[GBBUDD]

Most external pumps have a basket strainer to keep anything from getting sucked in that might damage the pump. How ever it does also chew up dinner partials making more nutrients within the pond

 

[sherry]

Most external pumps have a basket strainer to keep anything from getting sucked in that might damage the pump. How ever it does also chew up dinner partials making more nutrients within the pond

I'm looking at the PerformancePro Artesian 2 A2-1/3-63 6300GPH, do you think the High Volume Centrifugal Pump Intake Filter - 3'' would be useful?

 

[GBBUDD]

if it's something like this sure it can but if it's in the pond it could be a maintenance head ache. performance pro usualy has a strainer basket in a housing before the impeller

 

[sherry]

if it's something like this sure it can but if it's in the pond it could be a maintenance head ache. performance pro usualy has a strainer basket in a housing before the impeller

View attachment 158549

Great! money saved.

 

[sherry]

changing a 2 inch pipe to a 3 inch really won't increase volume without adding high pressure. A step from 2 inch to 3 inch is a lot more than you may think. 2" is good for 4500 gph a 3 inch if i remember correctly is over 13000. you can't push a round peg through a square hole without serious increase in pressure. and in this circumstance i doubt its possible.

two smaller pumps to push what a larger pump will uses less energy.

and if you have two pumps if one fails there's another already going to keep things alive

Just found a table and it shows (green columns) 2'' for 3300 gph and 3'' for 8400 gph. Is this the right table? If the new pump is 6500 GPH, it seems I need to use 3'' at the pump outlet according to the green column. I'm distributing the pump output to 3 small sized bogs (30sqft each). The pump sits very close to the bogs.
How about the pump inlet? should I use the red column (which means 2'' is enough for 6500 GPH)?

 

[GBBUDD]

My understanding is 4500 is average for a 2" under standard pressure. I'm no fluid dynamic engineer however. The chart says under normal it can do 7 with my pump I say not happening. Fluid dynamic is a science to the nth degree. Aquascapes i have been told, have helped out in design questions.

OVER SIZE FEED LINES ball valves to every pipe so flow can be adjusted .
a 2" pipe 5 feet from the pump and a 2 inch pipe that's 30 feet away that is tapped off a 3" line will not have the same flow rate
" fluid dynamics" ball valves to the rescue. but a word of caution you generally get what you pay for. imo schedule 80 ball valves while can be very pricey for any crucial frequently used should be 80's

 

[sherry]

My understanding is 4500 is average for a 2" under standard pressure. I'm no fluid dynamic engineer however. The chart says under normal it can do 7 with my pump I say not happening. Fluid dynamic is a science to the nth degree. Aquascapes i have been told, have helped out in design questions.

OVER SIZE FEED LINES ball valves to every pipe so flow can be adjusted .
a 2" pipe 5 feet from the pump and a 2 inch pipe that's 30 feet away that is tapped off a 3" line will not have the same flow rate
" fluid dynamics" ball valves to the rescue. but a word of caution you generally get what you pay for. imo schedule 80 ball valves while can be very pricey for any crucial frequently used should be 80's

Thank you. I read about using the 3'' as the body and multiple 2'' legs coming off of the 3''. I was going to size up the pump outlet from 2'' to 3'', but just realized it's a very short distance (2~10ft) from the pump to the bogs and with all the valves and wye fittings there is not much length that's actually using 3''. But maybe it's still better to over size.

 

[RMaynard]

Just found a table and it shows (green columns) 2'' for 3300 gph and 3'' for 8400 gph. Is this the right table? If the new pump is 6500 GPH, it seems I need to use 3'' at the pump outlet according to the green column. I'm distributing the pump output to 3 small sized bogs (30sqft each). The pump sits very close to the bogs.
How about the pump inlet? should I use the red column (which means 2'' is enough for 6500 GPH)?
View attachment 158584

The way I read it, you need to use the green column for the pipe inlet ("suction side of pump"), and the outflow from the bog ("Gravity to Low Pressure"). For the outlet of the pump you can use the Yellow ("average pressure"), but most like to oversize, so...

 

[sherry]

The way I read it, you need to use the green column for the pipe inlet ("suction side of pump"), and the outflow from the bog ("Gravity to Low Pressure"). For the outlet of the pump you can use the Yellow ("average pressure"), but most like to oversize, so...

This part I'm confused. I think water flow velocity at suction side of the pump = velocity at outlet of the pump (if they use the same size pipe) and both are at average pressure because of the pump (should use yellow column).
Outflow from the bog is "Gravity to Low Pressure" and could use green column.

 

[RMaynard]

This part I'm confused. I think water flow velocity at suction side of the pump = velocity at outlet of the pump (if they use the same size pipe) and both are at average pressure because of the pump (should use yellow column).
Outflow from the bog is "Gravity to Low Pressure" and could use green column.

I think it is about "what is pushing the water?" In the case of the bog outflow, and the pump inlet, it's gravity. This will achieve the lowest flow rates, and so you need bigger pipes (the green column). Only the pump outlet has the pump's pressure behind it, and therefore can achieve higher flow rates in smaller pipes (the yellow column). Most pond/aquarium builders try to have the least amount of head loss, so they oversize the outlet pipe, so back to the green column again.

 

[sherry]

I think it is about "what is pushing the water?" In the case of the bog outflow, and the pump inlet, it's gravity. This will achieve the lowest flow rates, and so you need bigger pipes (the green column). Only the pump outlet has the pump's pressure behind it, and therefore can achieve higher flow rates in smaller pipes (the yellow column). Most pond/aquarium builders try to have the least amount of head loss, so they oversize the outlet pipe, so back to the green column again.

That makes sense. Although I probably could argue that at the pump inlet water flows faster because of the pump pressure (not push out but draw it towards). But anyway, green column would be safe.
If 2'' has worked reasonably well for 4500gph, I assume in practice we may go by green column*1.3.

 

[GBBUDD]

What you probably don't realize is if you use an external pump they are terrible at pulling water ie the intake line. So much so if your pump is even a foot higher than the water source , there's a good chance it won't work at all. And submersible pumps can be tricky to convert to a pipe inlet source.