Sump Evaporation Rate Question

[werkkrew]

Well I finally turned my system on last night -

My setup is a 30G long display tank and a 20G DIY Sump which is set up with my return / skimmer in the first chamber, fuge in 2nd, and return pump in the last section.

When I filled my system last night I left the water level in my pump chamber slightly below the baffle line for my fuge so that there was a cascading waterfall into the pump chamber over the 10" high baffle.

When I went to bed the water in the pump chamber was about 8" high and all was well, but today I was woken up by the sound of my pump gurgling due to not enough water.

It seems that the water level in my tank is only noticable in my pump section of my sump (meaning, if you look at the system after a day, that is the only place the water level will be lower)

Since the way it was designed is almost identical to many other peoples setups, I am wondering, if my pump chamber holds approximately 3 gallons (in the chamber only), how could almost 2 gallons of water evaporate in the course of only 6 or so hours?


Should I fill my sump above the pump baffle line, so that there is 1 less waterfall and more total volume of water in my system? My understanding is that the last baffle is only really there to separate the contents of the fuge from the rest of the tank and to cut down on the available water to the sump in the event your overflow became clogged and your pump kept running.

I am also going to craft an acrylic lid for my sump tonight to hopefully cut down on the evaporation a bit more.

How much evaporation do you guys experience, is this normal?

[MalHavoc]

2 gallons of evap on a 50 gallon system in 6 hours is quite a lot. I evap about a half gallon a day on a 24 gallon aquapod, with no sump, and no cover.

[Shooter7]

Evap is good for temp control, and air exposure of the water is good for oxygenation. If your return pump chamber only holds about 3 gallons, and you didn't have it filled all the way thus getting the waterfall you spoke of, I don't think you evapped that much water. Nonetheless, your return chamber is where you will see your evap loss show up. I would level that off with the top of the baffle, then instead of closing it in with an acrylic lid (and also closing in heat, and closing out oxygen), I would put my efforts into getting an auto topoff setup going. Your return chamber is not very big and I would not be comfortable with it not having an auto topoff.

[werkkrew]

What if I run the water level an inch or two higher then the return section baffle? It would still be slightly lower then the baffle height coming from the overflow.

As for the lid, it wouldnt be totally enclosed, due to all the equipment in the sump, it would probably only cover 60% of the top.

I am going to look into auto topoff today.

[AquaReeferMan]

I lose about 2-3 gallons per day in my system. You will only see evap in the return section, so its key that that area be as big as possible. Try adding a pvc elbow to your return so its pulling the water from the bottom of the tank. A lid over the sump will cut down on it a lot.

[Shooter7]

I'm afraid I don't understand the point of running the chambers at different levels. My sump is level all the way across. What is achieved by the different levels?

[werkkrew]

Mine was totally level across when I initially designed it, but I changed the level of the sump return section as a last minute design choice because I was concerned that water would flow mostly across the top of the sump and not actually dip into the fuge and circulate properly.

The slightly different levels for me were chosen mostly due to seeing that method employed by many others and wanting the water to "swirl" around in the fuge rather then just skimming across the top of it.

[Shooter7]

I can understand the flow in the refugium point, as I had the issue of the water basically travelling across the top of the fuge and going into the return area as well, until I added a circulation pump to the fuge area. However, I don't see how having a water level that's lower in the return area would achieve improving circulation in the refugium chamber, as it would still just be dumping water off the surface of the refugium chamber into the return chamber.

[werkkrew]

Well the way I originally set it up was that I only added enough water such that the water in the return area was lower, on purpose.

If I add enough water to keep the water line above the baffle to the return pump I can still keep it an inch or two below the line where water enters the fuge keeping the circulation in tact.

I think I saw so much evap because I needed to add at least another 3 gallons to the sump in total.

Ideally Id like the tank to sustain 2-3 days before needing more top-off.

[sjm817]

That is a lot of evaporation. It doesn't sound right. My total volume is ~ 250g and I evaporate ~ 3G/day Winter, 2G/day Summer.