FiReBReTHa
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how much water should I expect to kick back into my sump from a 120g.
So when power goes out.
- Thread starter FiReBReTHa
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Depends on how your system is set up. I have a 300 tank and 125 sump. My sump is set up to hold about 60-70 gallons. When the power goes off, I have 2" of back flow in to the sump. That leaves me about 9" before I overflow.
It all depends on the elevation of your overflow box and stand pipe and your retrurns. On my 100G it drops about 3/4" which equates to about 3.5 gallons.
Always keep your returns close to the surface so in a power outage the tank level will only drop to that point beofe it breaks suction and stops the siphon effect. The lower the returns the more water you can expect in your sump. Some will recommend drilling holes in the returns below the surface but this is a flood waiting to happen. Drilled holes require maintenance and we all tend to get lazy over the years, forget to clean them or let a snail park over the hole and its a flood in the making.
Same goes for check valves, they are not designed for dirty water, all it takes is one grain of sand, some food, a piece of algae or a small snail and you defeated the valve and again the flood is on.
I follow a few simple rules. Keep the returns close to the surface and always maintain at least that much freeboard or more (I maintain 8 gallons of room in the 30G sump always) in the sump to contain the worts case scenario backflow. I usea Sharpie to mark my high and low operating levels and my high level when topping off on the side of my sump and never ever fill past those marks even if you are going to be away for a few days.
To calculate how many gallons and inch of water is in your tank or how much you will back siphon if you know the level multiply the length in inches by the width then divide by 231 for gallons per 1 inch. For more than and inch multiply the length times width times the drop in inches and again divide by 231.
In my case its 60"x18"x.75"= 810 divided by 231= 3.50 gallons if it was a full inch drop it would be 4.67 gallons so my 8 gallons of spare room is always enough even if I dropped my returns a little lower. I try to keep they about the same level as the bottom of the slots on my overflow box so both quit siphoning about the same time.
You can calculate how much the sump holds per inch the same way L"xW"x1" divided by 231. My sump is a 30G and holds like 2.5 gallons per inch or something like that I think.
Always keep your returns close to the surface so in a power outage the tank level will only drop to that point beofe it breaks suction and stops the siphon effect. The lower the returns the more water you can expect in your sump. Some will recommend drilling holes in the returns below the surface but this is a flood waiting to happen. Drilled holes require maintenance and we all tend to get lazy over the years, forget to clean them or let a snail park over the hole and its a flood in the making.
Same goes for check valves, they are not designed for dirty water, all it takes is one grain of sand, some food, a piece of algae or a small snail and you defeated the valve and again the flood is on.
I follow a few simple rules. Keep the returns close to the surface and always maintain at least that much freeboard or more (I maintain 8 gallons of room in the 30G sump always) in the sump to contain the worts case scenario backflow. I usea Sharpie to mark my high and low operating levels and my high level when topping off on the side of my sump and never ever fill past those marks even if you are going to be away for a few days.
To calculate how many gallons and inch of water is in your tank or how much you will back siphon if you know the level multiply the length in inches by the width then divide by 231 for gallons per 1 inch. For more than and inch multiply the length times width times the drop in inches and again divide by 231.
In my case its 60"x18"x.75"= 810 divided by 231= 3.50 gallons if it was a full inch drop it would be 4.67 gallons so my 8 gallons of spare room is always enough even if I dropped my returns a little lower. I try to keep they about the same level as the bottom of the slots on my overflow box so both quit siphoning about the same time.
You can calculate how much the sump holds per inch the same way L"xW"x1" divided by 231. My sump is a 30G and holds like 2.5 gallons per inch or something like that I think.
Last edited:
Sikryd
hmm...Sweet!
RC has calculators on the left hand side of the homepage for all of that stuff if you want to get an estimate.
I used it for building my custom sump and stuff.
Like always I pull all the plugs to test it out though ;)
I used it for building my custom sump and stuff.
Like always I pull all the plugs to test it out though ;)
beaslbob
2500 Club Member
I presume you have return lines with 1) the end above the water line or 2) have anti siphon holes drilled. If not then the return lines will Drain the display down to the bottom of the return lines. 1/2 way down would be 60g :wink:
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