water change help

[dviper150]

I am starting a sump/refugium this week and the water is going to them by 2 overflow boxes on the back of my tank. I have 2 sumps setup under my tank. One of the sumps only has 2 chambers and I will be using one of those chambers to house live sand, live rock, and some chaeto. the other chamber being the return pump. The other sump has 3 chambers. the middle of the 3 chambers is where i will have the in sump skimmer setup and the first chamber or the inflow of it I will have a second refugium part with live sand, live rock, and chaeto.

My question is, when it comes to doing water changes, do i just suck the water out of the sump or the DT? either way, the water level in the tank will go down and wouldn't that cause the overflow boxes to stop the suctioning? if that is the case, is there a way around this in which the overflow boxes keep flowing?
Any help or suggestions would be appreciated. Thanks.

[shroutk3]

The majority of overflow boxes that I have seen have provisions that keep them from losing siphon. If yours does not, you should be thinking about what will happen in the event of a power outage- i.e. when your pumps restart, will your tank flood? You should probably test this (stop then start your pumps and see what happens). The good boxes have partitions in them that maintain water in the U-tube.

If you have a box that maintains siphon, then no worries. I water change mainly out of the sump with the pump off. The display doesn't drain more than an inch or two. I do this mainly so that the new water doesn't directly shock corals or fish, and comes up more slowly from the sump. Occasionally, I change from the tank in order to suck up detritus and such

[carpas]

I like to siphon as much as I can from the display to get the gunk out of the rocks. (Incidentally this points to inadequate flow in my tank but I'm upgrading so it doesn't concern me.) Assuming your overflows can restart you won't have a problem doing it this way. This also assumes your return section can handle that much water being removed w/o sucking air. For larger changes I need to turn off the return pump for a few minutes. The new water is then added to the sump.

[lordofthereef]

I find it easier to water change out the the display and then add the amount of water I removed into the sump. This is simply because the siphon is faster and easier whan it is flowing from higher up, but either method works. Your overflow box shouldn't lose suction. If it does you could be in trouble during a power outage. Did you make it or is it store bought? If it is store bought and set up per manufacturers specifications I am sure it is self-priming.

[Jason Donohoe]

One thing that has not been mentioned is your return line. It should be just under the surface of the water in the DT or have holes drilled just below the surface. This way when the power goes out it will limit the amount that drains back into the sump before the siphon breaks. Make sure there is adequate room in your sump to accomadate this back flow. As already stated, your overflow should maintain the siphon but I would sure watch it closely when you turn the power back on if you're not sure!

I turn off my return pump and suction the water out of the sump with an old maxi-jet connected to a length of 1/2" tubing. I then pour the new ASW into the sump and turn the return pump back on.

Good luck.

[Sig45]

Can you put a T valve on the overflow line and just divert exchange water that way. This would maintain you siphon.

[dviper150]

forgive me about this but I am not familiar with any of the plumbing yet because this will be my first time setting a sump up. how will the T valve divert the exchange of water if I only put one pipe from the overflow box going down to the sump?

Again, I am sorry about naive but this is my first time setting it up and am still learning along the way.

[-Pixie-]

I have a similar problem to you, as the water level decreases the siphon stops and my sump gets drained near dry, i turn my return pump off stop my siphon do the water change and then switch everything backon and restart the siphon.

[-Pixie-]

If not could you add water to one side while draining from the other?

[dviper150]

How would do that? draining sides of the tank? The water goes down equally in the whole tank if I drained directly from the DT.

[Sig45]

I was referring to doing a 1:1 exchange. Divert overflow water to discard via T and at the same time add fresh SW to sump with pump on.

[dviper150]

oo ok...i understand.

[Jason Donohoe]

Check out this site: http://www.lifereef.com/siphon.html

These overflow boxes are designed to retain their siphon with power outages. You just turn everything off, do your water change, and turn it back on. I have a similar overflow on my tank and it works great.

[bbl_nk]

I built my own overflow and used the same method Jason posted about. Works great and doesn't lose siphon. The only time it does is when I take the tube out to clean, then I have to break out the airline tubing to get it back.