What size pump???

[anfo]

Hi,

I'm in the process of setting up a rack system involving 5 tanks that are 4x18x18...

These 5 tanks will be plumbed into a sump...

How do I work out what size pump to run for the sump???

 

[Lornek8]

It depends on what you're trying to do and how your tanks are setup.
Things to consider:
1) Desired flow rate through tanks.
2) Height difference between highest pipe and pump.
3) Overflow/return setup and pipe sizing.

 

[anfo]

It depends on what you're trying to do and how your tanks are setup.
Things to consider:
1) Desired flow rate through tanks.
2) Height difference between highest pipe and pump.
3) Overflow/return setup and pipe sizing.

Height would be 2 metres high and return pipes I think 25mm...

 

[bigbird]

i would reconsider the sump, as each different L has a different temperature range and with the sump, if one tank has any disease, then the others will also get this. I would go to your LFS and ask them, they can usually calculate this for you. Also remember that the sump must also hold enough water if you have power failure as water from all tanks will drain to the point of where your hole for the sump out/inflow is. cheers jk :thumbup:

 

[Lornek8]

Height would be 2 metres high and return pipes I think 25mm...

And what type of flow rate are you looking for? The max the pipe can handle or something lesser? You just want to make sure that the pipe can handle a flow rate greater than the pump capacity. Are you overflowing back to the sump or siphoning?

 

[anfo]

I would like to get the most flow from the pipe...

The tanks are drilled with 30mm standing pipes...

 

[Lornek8]

How are the tanks configured? Are all the tanks atop each other so that water is pumped into the top tank and flows down into the remaining or is it divided into a number of columns?

Based on gravity flow, capacity for 1" (25mm) pipe is about 960gph. If you size the pump around this size you'll probably be okay though that's a pretty high flow. You want your pump to have slightly less capacity than the pump so you don't happen to pump more water into the tanks than the over flow can handle.

Sent from my KFTT using Tapatalk 2

 

[anfo]

I'll have 2 tanks at top, then flows into the 2 middle tanks and then 1 on ground level then into a sump also on ground level...

 

[Lornek8]

Are the two columns of tanks on top/middle both going to go into the bottom tank then into the sump? Think you'll have problems getting from the ground level tank then into the sump due to lack of elevation difference.
Sent from my KFTT using Tapatalk 2

 

[anfo]

The 2 tanks on the top will drain into the 2 in the middle...

From there, One will drain straight into the sump, which is located directly below it...

The other tank will drain straight into the tank on ground level. This ground level tank has a hole drilled into the side panel, so the plan is to have the water run sideways into the sump...

 

[Lornek8]

Theoretically you could go twice the 960gph since you have to paths back to the sump. Seems like quite a bit of flow through those tanks though. My recommendation would be simply to pick a flow rate and size the pump for that. I'd also build in a bypass and flow control valves to fine tune the flow rates.

 

[anfo]

I'm thinking a 5000L/hr pump with a head height of 3.5 metres??? (pump hasn't been purchased yet so can still change my mind of need be)

Why do I need a bypass???

Do I put the valve control on pump exit???

 

[anfo]

Height of highest tanks are at around 2 metres, and I know it won't be pumping anywhere near that 5000L/hr at that height...

Should I be going bigger??? Say 6500L/hr???

 

[Lornek8]

The height a pump can pump to is pump specific. You can get some pumps that have high flow rates but little head (height). You need to start looking at pumps to determine what type of rating they have (most pumps list the head specifications, some even lists flow at various heights).

With these type of pumps what you get out is what you get out. If for some reason you choose a pump that puts out more flow than you require or your system supports, than without a bypass the only option you have is to get a new pump or redo your piping. With a bypass already built in you can tune the output flow. What I'd do is to have 3 valves on the outlet of the pump. 1 bypass to the sump and 1 at each of the tank inputs. That way you could control flow to each set of tanks. Say for instance that something happens to one of the tanks. You could shut off flow to the one set of tanks and slightly open the bypass to still allow the other set of tanks to get flow without directing all the flow to a single set of tanks which would exceed the capacity of the drain pipes and overflow the tanks.

 

[anfo]

Yeah, the pump I'm lookning at has a head height of 3.5 metres with a flow rate of 5000L/hr at zero.