Automatic Water Changing at the Sump

[joobie]

Hi All,

I have a Herbie based overflow setup running to a sump. I wanted to do an automatic water changer at the sump and am not sure about how to achieve it.

Ideally if it can be done without a pump this would be great, but not sure if I can achieve that safely. I figured I would drill the tank at the top and put a 2" emergency drain at the top of the tank. 2" because I have a 3/4" siphon and a 1" emergency overflow in the display tank, which will both feed into the sump.

I'm not sure though how to get the water out of the sump and get the new water in safely. I can place a reservior of water above the sump so it can gravity feed in and also place the drain below the sump to gravity feed out. But when I read about doing this with solenoid valves, people talk about the downsides where by there might be pieces of gunk that will go out the valves and potentially when they close, stop the valve from sealing properly if a piece of gunk gets caught.

It sounds risky.. just wondering how others would go about achieving this?


Thanks, Richard

[thegrun]

I have always used a pump. I would worry about a gravity system draining into the sump causing a flood and a sudden change in salinity. I know others have used a gravity system but I would feel safer using a small pump.

[rustyjames]

Automatic,to me, means it would be done without human intervention. Without a pump it seems nearly impossible to me. There are products, a little pricy, that will do small, frequent water changes.

[Acronic]

you could put an overflow in the sump, just a hair above the normal water level and plumb it to a drain. Once you add new water to the sump or wherever, the water level in the sump will rise and overflow the excess into the drain. No pump. If you used a solenoid valve on the holding bucket that would make it "without human intervention" but a ball vale is just as easy and cheap.

[joobie]

Thanks for the response guys.

The issue I see with the pump is that if I pump out water from the sump and then pump the new water back in after - to do it safely i'd need to stop the pump going back to the display tank. This would cause the water level in the display tank to stop and also the Herbie style siphon. Then when I pump the water back in and restart the pump to the display tank, the Herbie should kick in again, but i'd rather be there watching when the Herbie kick starts (rather than restarting it many times unattended).

The idea about placing and overflow in the sump above the normal water level, and feeding new water in to cause it to overflow is one i've looked at. I was deterred from this solution as people say that it's better to drain the water and fill the water separately, so that you don't end up losing some of the new water down the overflow.

Is there a way around this? I really like the idea of doing it without a pump. If I for example had the overflow at the far left of the tank (where the water came in from the display tank) and then put the fresh water in at the side of the tank that pumps it into the display tank, would something like this work and be enough distance to stop filtering out the new water?

Any other methods?


Cheers

[Acronic]

I think the loss of fresh water would be negligible. Separating the fresh salt water from the overflow is a good idea. If done that way i bet very little fresh salt water would go to waste.

The overflow only skims the top layer wich is the dirtiest in theory. So either way you are wining :)

[Acronic]

Also if you remove water before adding, it would activate the ATO and shift the SG over time

[joobie]

Thanks Acronic.

Interesting comment RE dirties part of the water being the top. For knowledge sake what is it that is rising to the top in the water? I was thinking all this time it's the protein in the water that rose to the top and is only really beneficial for a salt water tank to do - but now I went with it anyway as it suited the Herbie overflow method.

Oh BTW, what does ATO and SG stand for?


Thanks, Richard

[Acronic]

Ya ur right the dirties are protiens, oils and small particulate matter, dust ect.

ATO stands for Automatic Top Off. Lots of people use a float switch to add RODI via a controller to combat evaporation.

SG stand for Specific Gravity, the salinity level of the water :)