Sump overflow and semi-automatic water change

[dowsetts101]

Hi all, I wouldn't mind your thoughts on my sump and water changes.

I'm in the process of finishing off my sump and am trying to work out a semi-automatic water change. I plan on having a 3 way valve on my return line to my DT from my sump.

I'd then have a pipe coming in from my new salt water mixing tank into the 3-way valve.

I'll also need to drill an overflow for the sump directly to drain.

So the process to do a water change would be:
1. Turn of main return pump to DT
2. Change the 3-way valve to select the NSW pipe
3. Turn on pump from NSW tank
4. NSW would then go into the DT
5. As the NSW displaced the water from the DT, the sump would fill up and start to overflow to drain
6. When NSW tank empty, turn off pump, change the 3-way vale back to the main return pump
7. Turn on the main return pump...and all done.

I've done a sketch of what I'm thinking below.

I have a concern around actually letting the sump essentially overfill and overflow (in a controlled manner) but as this is only whilst I'm doing a water change I reckon it would be ok for a short period of time.

Does anyone see any issues with what I'm planning?

 

[moseley75]

At what depth does the sump overflow keep the sump? Can you stop the flow into the sump overflow?

 

[dowsetts101]

I'm still working it out. Overall depth of sump is 450mm. Water level in chamber 1 is 300mm, chamber 2 is 275mm and last chamber is return pump ( so variable)

I was going to drill a bulkhead overflow at 400mm, so 50mm below overtopping of the sump and 100mm above highest normal operating depth...if that makes sense.

 

[moseley75]

I would put a check valve in the line between the display and nsw pump to prevent backflow.

Also, I believe that normal operating depth of the sump would be set by the sump overflow.

 

[dowsetts101]

I would put a check valve in the line between the display and nsw pump to prevent backflow.

Also, I believe that normal operating depth of the sump would be set by the sump overflow.

Good idea on the check valve...I need to remember to put a few of them in.

Isn't the normal operating depth of the sump set by the height of the weirs or baffles in the chambers and by the performance of the return pump in drawing down the water in the return pump chamber.

When doing a water change, the level in the sump would be set by the sump overflow...unless that is what you meant

 

[moseley75]

My sump has the baffles that are full height and slots cut for water flow. I can over fill it. I assume, if you keep adding water to any sump it will fill up to the rim or overflow. The baffles won't matter.
You should make sure that the overflow drains faster than the supply or you can cause a flood.
I like your idea. I've been thinking how I would do this myself. I live in an apartment so would have to use hoses for nsw supply and the drain.

 

[dowsetts101]

I'm with you now...I've left my baffles/weirs lower than the overall sump tank depth, to allow for extra capacity for drain back from DT in event of return pump shut off. I originally hadn't thought of sump overflow, but as I've been thinking about the NSW fill, I reckon I can kill two birds with one stone..allow for water change, and have overflow.

I'm thinking that for the overflow, I'll drill a bulkhead in one of the sides of the sump, then put a 90 deg elbow on the inside, pointing up, so that the intake to the overflow is just shy of the top of the sump.

I was going to go a 1" overflow...but now am thinking that I should at least match my outlet from the display tank 1 1/4" to be sure.

Just finished siliconing the last baffle in my sump tonight...now I have to go back and drill it....would have been so much easier when it was flat glass!!!

Thanks for your thoughts.

Pic of my sump...fumes and all!!!

 

[moseley75]

Nice looking sump. I have an Eshopps cube nano. I haven't flooded my apartment yet but I have over filled it which caused my skimmer to overflow.

 

[dowsetts101]

Just thinking about your comment about the check valve. If I have a check valve on both the NSW and the return pump pipe as well...why both about a 3 way valve...if the return pump is on, the check valve on the NSW will activate, and if the NSW pump is on the check valve at the return pump will activate.

Achieves the same result without using a manual valve.

Hmmm...will need to think a bit more about this I think!!

Instead of a 3 way valve which I manually have to select, if I put a check valve

 

[dowsetts101]

Discussed this with the guy at the plumbing supplies place today and he agreed that the check valves will work well.

In the end I went with one each of two different types. One is a PVC gate style valve the other is a Poly spring loaded one.

The PVC one is easier to open so I figure will have less head loss across it, so I'll use that on the return pump line as it will be 'always open' except when doing a water change.

The Poly one I'll use on the NSW line. It's a stiffer arrangement and would appear to have a greater head loss. On the NSW line it will be 'always closed' so I think this will work well.

It will be a few weeks before I can connect all this up and run my wet test and I'll let you know how I get on.

 

[moseley75]

The gate type are more prone to failure due to a small bit of trash. I'd get ones that can be easily disassembled and cleaned.

 

[moseley75]

Side note. My younger brother lived in Australia for a while. They could see that building in the background of your avatar from their balcony. I always wanted to visit but they left for Germany before I was able.

 

[dowsetts101]

Side note. My younger brother lived in Australia for a while. They could see that building in the background of your avatar from their balcony. I always wanted to visit but they left for Germany before I was able.

Sydney Opera house. I'm in Melbourne but that photo was taken when we were leaving for a cruise. Australia is pretty cool...but long way to get here. Can't just drop into OZ...gotta be a deliberate destination and be happy with long plane rides!!

 

[moseley75]

LOL. I love to fly. Became pilot at 15. Wanted to visit and dive on great barrier. Just had family obligations. You know, children. Little buggers are expensive.
Living there was a great experience for brother and his wife.

 

[dowsetts101]

And just to close the loop...here is the sketch of my plumbing fittings that I used to order all my stuff. Lots of check valves, tees, elbows.

Not sure about the valves that I got, but it's a start anyway.