2 tanks 1 sump - what pump power?

[basoikan]

Hey guys,

I'm planning to have 2 tanks (100gals + 50gals) filtered through one sump.
Both tanks have overflow boxes with 2 1" bulkheads in each. The return pump will be split into two, feeding clean water into each tank (can be further adjusted via ball valve)

I have a choice of these two return pumps:

3500 l/h (around 850gph - max head 3m) or 5000 l/h (around 1250gph - max head 3.5m)


The sump size is around 20 - 25 gals.
I'm confused whether to go for the smaller pump (less electricity) or the bigger one (more flow), but afraid of draining the sump.
I'm leaning towards the 3500 l/h but will there be enough water pumped back?
The water will be pumped up around 1.5m high back to the tanks

Opinions please ......

 

[cjack]

Don't worry about draining the sump, so long as the drains can handle the flow you'll be fine. The trick will be fine tuning the flow to each tank, but with a ball valve on each side of the T it won't be too hard.

 

[basoikan]

ok ... another question, if i join 2 x 1" (25mm) drains into one 32mm through gravity fall from the overflow, will the flow be as much as having 2 separate 1" going down ?

 

[Jer]

*wonders how many people found this thread after a Google typo* lol

 

[KAWAMIKIE]

The larger pump will be fine. A 1" drain will flow approximately 600 gph.
Look at this thread for pipe sizing and flow rates.
http://www.monsterfishkeepers.com/f...Pipe-Sizing-Charts-and-Flow-Rates-(3-Viewing)
Draining the sump is not the problem, it's overflowing the tank you need to worry about or overflowing the sump in a power outage.

 

[duanes]

Never skimp on "pipe" size to the sump if you combine 2 outflows into 1, double the size pipe to the sump after they are combined. It is very easy for debris to get caught up in the Tee of small pipe and then overflow the main tank. I have had a dead fish combine with snails and plant parts and block a 1" pipe more than once. (I prefer 1.5 or larger for drain lines)
I always use the largest pump possible and throttle the flow back if needed, you never know when you might want to add a 3rd or 4th tank. Or add fish that require a stronger flow.
Below is a 20 gal sump using an 1200gph pump, note the size of the PVC line to sump return (white one) it is 2"

 

[cjack]

You can absolutely splice the two drains into one, but as everyone else has said, you have to at least double the diameter. I would offer a word of caution with valving pumps down, as it reduces the amount of water that can cool the impeller and forces the pump to work harder, resulting in pumps burning out faster.

As Kawamikie said, overflowing the sump is an issue, so when you set up the sump let it run for a little bit and get to its operating level. Then unplug all of the return pumps to simulate a power outage, then you can adjust the water level to figure out your maximum fill level so you don't flood.

 

[imtcurveball]

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