Simple pumps vs. complex gravity - opinion requested

[Mr. Brooks]

Hello large tank forum! I'm at a crossroads. I'm building a large interconnected system. It consists of a 390 gallon display in my office, with a 100 settling tank, 180 gallon grow out tank, two sumps and a pax bellum cheato reactor behind the wall in my warehouse.

I'd planned on running 4 pumps. Two pumps to the display (for redundancy), one pump to the 180 grow out tank, and 1 pump to the pax bellum and various reactors on a manifold.

If you look at the picture below, you will see that the settling tank is quite tall. Almost as tall as the display. If I choose, I can drill a hole below the normal water level in the settling tank, and gravity drain water to the 180 gallon grow out tank and reactors.

This will add some complexity and fine tuning to my system, but I would be able to do away with two pumps. Use less electricity, have less pumps to clean, and two less pumps to worry about failing.

The only trouble is, it will not be as easy to isolate the components in my system. Every reactor or tank in my system will be interconnected, adding complexity. If I need to shut off the pumps to the display, I'm shutting off water to the whole system. It's convenient to have each tank/reactor on a separate switch. But is it necessary?

My question to you is what would you do? Gravity drain with complexity and fine tuning? Or add two pumps for simplicity.

 

[dave.m]

I always go for more pumps - greater control of flow, easier to segregate components for maintenance, ease of operation, smaller disaster in case of failure. Saving energy and costs is a noble pursuit, but I always put reliabilty and security (and sanity) first.

Dave.M

 

[Mr. Brooks]

I should mention, I have backup drains to prevent overflows.

 

[slief]

I'd gravity drain from the display to the settling tank but plumb in bypass lines so you can isolate the settling tank and associated components by closing/opening a valve. That would allow you to shut down the settling tank or anything else without having to shut down the return pump.

In my case, tank feeds my sump via the overflow. My refugium is plumbed downstream of the sump and the return section where my pumps are located are at the end of the refugium. I have a bypass line that goes from the sump direct to the return inlet. I can close one valve, open another and completely bypass the refugium if I need to do maintenance on it.

While the bypass lines may add plumbing complexity to the system, there is something to be said about reducing pumps and maintenance. I'd also point out electrical savings but given your solar setup, that isn't much of a factor.

 

[Mr. Brooks]

Good call. I'd already planned bypass lines around the settling tank. The solar setup doesn't provide unlimited power so at a certain point I have to start paying. I'm trying to stay below that point.

Right now I'm leaning toward gravity draining to the grow out tank and the pax bellum reactor. I'm thinking I'll run the calcium reactor on a pump so the apex can shut it off if need be. I'm not always going to be running media reactors so I'm thinking I'll put those on their own pump as well. The less constant fiddling and fine tuning the better.