height of baffles? - sump

[~RuSh~]

I forget the formula for calculating baffle height for my sump - so in a power outage my sump doesn't over flow... any help here?

40g breeder display - 700 glass holes overflow kit (on the way), 20g high sump tank.

Any help is appreciated. Thanks.

[davocean]

I'm not certain if there is an actual formula, I base what I do by my own experience and ability to eyeball it, but I'd say your sump will most likely be about 3/4 full, and that is going to vary some depending on where your returns are in tank.
I keep locklines up as high as possible for early siphon break, and this allowed me to cheat that volume a little higher than 3/4 on my present sump.

[Vinny Kreyling]

I find 1/2 full works on most sumps, this allows for enough extra space if the pump goes out.

[MikeInToronto]

When I build a sump, I make sure the baffle for the skimmer chamber is at the recommended height for the skimmer (usually 10"). The rest of the baffles don't matter unless you're doing something fancy with the sump.

I added a pic of a simple design. The red baffle needs to be 10" (for my skimmer). The rest can be whatever as long as any baffles after the red one that touch the bottom pane are less than 10" (i.e the 3rd baffle is this case).

If the sump baffle is too high, you may end up having to lift the skimmer so it doesn't overflow. But also make sure the return pump chamber is deep enough. Generally I make the 3rd baffle 9".

[davocean]

I think most of us end up putting our skimmers on a platform of some kind, my skimmer pumps does best in 6-8" which would be too shallow for me if my whole sump was at that level, but I want to have max fuge for pod space, so I want max water level in my sump.

[MikeInToronto]

Originally Posted by davocean

I think most of us end up putting our skimmers on a platform of some kind, my skimmer pumps does best in 6-8" which would be too shallow for me if my whole sump was at that level, but I want to have max fuge for pod space, so I want max water level in my sump.

I guess the real answer is, decide what he wants his sump to do and the rest of the design falls into place. My sump is relatively large (75 gallon stock tank) so most of my water is wasted space. Sure, it's nice to have the extra volume but I don't really use it - my fuge is separate. I guess it also depends how much height is available under the tank stand. If there isn't a lot of room to raise the skimmer, he might not have a choice how high the baffles can be.

A 29 high doesn't have a very large footprint after the skimmer is added. There is enough room for the skimmer and a return so I don't think he could add much more. I could be wrong.

To the OP, measure down from the tank's water level to the level where the water would leave the tank in a power outage (either the return line or the overflow, whichever is lower). Multiply length x width x this level. Divide by 231. That's the number of gallons that will leave the tank during an outage.
Now measure the height of free space above the water level in the sump when the tank is running. L x W x this number, divide by 231. Make sure this volume is higher than the water leaving the tank and you're good.

[Lsufan]

With a 20 H sump I would just make the baffles 9 or 10” & put the skimmer on a stand. I really don’t see a reason to be more then 10” & that would still leave plenty of room in the sump. I would probably just go 9” to be on the safe side & that is still plenty deep for any skimmer for a 40 b.

If it isn’t to late I would consider a 20l instead of the 20h. It makes it easier to work in the sump only being 12” tall. If u go that route I wouldn’t make the baffles any taller then 8”.

Btw, how your returns are plumbed is what will make the biggest difference as far as how much water drains to the sump when the return pump is off. With drilled returns u have to be careful because u can get quite a bit of water to the sump. With over the back returns u can set it up to where u have very little drain down

[~RuSh~]

Yea I'll be using a loc line return with a y. But if I just keep one of them up high won't that act as a siphon break? Even if the second is pointed downward?

10 inch baffles should be good. Last baffle at 9 probably what I'll do. Just want to make sure I don't flood the sump in a power outage - how solid are check valves on return lines?

[~RuSh~]

Originally Posted by MikeInToronto

To the OP, measure down from the tank's water level to the level where the water would leave the tank in a power outage (either the return line or the overflow, whichever is lower). Multiply length x width x this level. Divide by 231. That's the number of gallons that will leave the tank during an outage.
Now measure the height of free space above the water level in the sump when the tank is running. L x W x this number, divide by 231. Make sure this volume is higher than the water leaving the tank and you're good.

Thanks!! That's what I was looking for!

[Lsufan]

How are your returns? Are they drilled in the back glass or doe the come over the back of the tank or overflow box.

If they are drilled in the back glass then the tank will drain down until both locline are completely out of water. If over the back then as soon as they suck air it will quit draining. It’s good practice to leave the returns as close to the surface as possible.

If u set the returns up to where u only drain about 2” of water from the dt then u will be ok with 10” baffles. If it drains 2” of the dt it will end up draining right around 6 gallons of water which a 20h sump should be able to handle with 10” baffles. If u go with 9” baffles u should have about 2 gallons spare in the sump for safety Incase a locline gets pushed down a little more then what it is supposed to

[~RuSh~]

Nothing is drilled as of yet, but yea that is what I plan to do. Drill the return, and have the loc line split. Dang, yea guess I'll have to keep them up fairly high then.

Thanks for the heads up.

[davocean]

Yeah I guess Mike in T explains better what I do w/out putting a lot of thought into it and does actually formulate this better.

I do look at the overall surface area and am a pretty good estimator of how many gallons are going to back siphon, and I keep my locks up high to keep that to a minimum, and agree w/ LSUfan about 2" down on returns is a good height.

So basically like Mike said, and to make it even a little easier there is a tank volume calculator on the home page so you can figure volume of back siphon and space needed in sump and build accordingly.

[~RuSh~]

OK I did some measuring and calculating here. My display is a 40 breeder so 36X 18 X2 should give me the number of gallons that will drain from the display in the event of a power outage. =5.6 gallons.

The recommended water level for my skimmer is 11 inches high so my first baffle will need to be 11 inches high. That leaves 5.5 inches above the tallest baffle. My sump is a 20 gallon hi so 24.5 X 12.5 X5.5 equals 7.29 gallons.

The last baffle won't be quite as high as the first so I will actually have more space than that available in the sump, so I should be covered there.