Tank Drain Location

[docsavage]

So below is my initial layout (don't be too harsh) of my next tank.

My last problem is to solve the water change / drain issue. My goal is to easily drain 40-50 from the tank, then use a container of premade SW to fill the sump back up. I need to know where to connect the big question mark to. Obviously I want it pretty failsafe and there be NO chance of it draining too much when I'm gone. I also can't do anything to do sides of the tank or the back, so it would have to be in the overflow section inside the tank.

Because this is plumbed to the kitchen, I'll connect the drain / RODI fill to the house plumbing. The goal was also to keep the pipes connecting the sump and topoff tank open because they are the same height, that way the float switch could monitor the sump level via the topoff tank.

Any ideas?

 

[DaveWC]

I don't understand how you can drain 40-50g when your top off container is only 20g. And if the 20g is a misprint, it seems odd to me to have the kalkwasser as part of the water change system rather then going direct to the sump. Maybe I've misunderstood your drawing and the Kalk/20g system has nothing to do with water changes.

Assuming that the refill part of the w/c is not on the drawing, I'd drain the water from the sump. In my system the sump is large enough to remove all water for the w/c from the sump, while the pump is turned off. I just close a valve on the return line to stop water from going to the tank and open a valve on the same line to divert water to the drain. When the sump is empty I turn on the pump in my holding tank to refill the sump. The just set the valves back the way they were to begin with and the tank can get back online. It takes about 5 minutes.

 

[docsavage]

You are correct...the topoff system has nothing to do with removing water. The new SW would come from a 50 gallon or so container that would be pumped into the topoff container or sump. I'm only concerned about getting old water out of the tank/sump.

How you did yours was kind of how I was thinking... plumb the return from the pump with a T-valve and just divert water from the sump to the waste drain via the return pump. Only problem I i'll have to make sure the return area in the sump is large enough. Was only planning like 55 gallon for the whole sump, so might have to rethink that.

 

[DaveWC]

My sump area holds about 15g and my tank is 67g. On my return pump I can divert the flow to my house drain. So I just pump out the sump to the drain, and while I'm doing that I siphon a couple of gallons into the sump from the refugium because the pump won't drain the entire sump, it leaves about an inch of water. When the sump is empty I refill from the holding tank.

I'm putting together a 225g tank in the room next to where the 67g tank is. The line from my holding tank will run from the 67g tank to the 225g tank so I can refill either sump. This line also diverts to the house drain. So what I'm saying is I can reuse the same line of pipe to fill & drain my two tanks. I use the pump in the sump of each tank to empty and the pump in the holding tank to refill. It's just a matter of having valves to control which direction the water flows and where it goes.