New to Manifolds - Return Pumps

[Socals14]

Setting up my tank again - third time I have done this - and I always take the time to see if I can mix it up. New for this time will be a manifold. I have a chiller and Phosban reactor and I thought why not drop the small pumps I have feeding these? I use 1" returns, so I can easily go with 3/4" gate valves on the manifold. That seems to be the easy part. The tough part is my return pump. My return pump is an Eheim 1262 - has always been reliable. However, with the manifold, I will need to consider the additional head pressure. This has me thinking this may be the time to try out a controllable DC pump.

How do you calculate the additional head needed from the manifold?
Given DC pumps are controllable - how much head room should I purchase in such a pump?
I have dual return - would it be worth buying two smaller DC pumps - one for the manifold and a backup?

 

[kharmaguru]

I think a manifold would reduce head pressure not increase it. I am guessing it would become a division of your output by the number or ports the manifold has, so total flow would be mostly unchanged but individual port flow would be reduced. You need to ascertain what flow you want for each of your appliances and then what remains - remains. Then you'll know wether you need a bigger pump or not.

Maybe @BeanAnimal has a better answer.

 

[BeanAnimal]

Head loss = vertical head loss + friction head loss

Adding length of pipe increases friction and direction changes and valves, etc cause turbulence (more friction). You can calculate all of this, but it is not really worth it. If the eheim is close to the sum of the individuals then you will be close. If more than 4-5 years old I would replace it anyway. Get a DC pump larger than you need. Dial it back and it will last much longer.

 

[mtnbike101]

This^^^

Tank size?

 

[BeanAnimal]

And yes a dc return pump for each return is not a terrible idea. Gives you redundancy and allows you to run them at less than full power.