chrisfowler99 Posted February 19, 2009 Share Posted February 19, 2009 Tank is 75g Sump is 29g (30x12x18) Octopus NW-150 skimmer is on the way and it's rated for 8-11" of depth, I believe. I have a bit of wiggle room for raising it a few inches if I choose to do so. My gut says to go with 12" for the baffles giving me decent water volume for the sump while still having some wiggle room for overflow from the tank should the pump shut down. Quote Link to comment Share on other sites More sharing options...
+Capt. Obvious Posted February 19, 2009 Share Posted February 19, 2009 Tank is 75gSump is 29g (30x12x18) Octopus NW-150 skimmer is on the way and it's rated for 8-11" of depth, I believe. I have a bit of wiggle room for raising it a few inches if I choose to do so. My gut says to go with 12" for the baffles giving me decent water volume for the sump while still having some wiggle room for overflow from the tank should the pump shut down. sounds about right...are you talking about the highest baffle or the bubble trap baffles Quote Link to comment Share on other sites More sharing options...
chrisfowler99 Posted February 19, 2009 Author Share Posted February 19, 2009 Baffles would be 12x12 (actually 12x11 1/2 as that's the interior depth of the tank) The middle bubble trap baffle would be raised an inch making the top of it 13 inches off the bottom. Quote Link to comment Share on other sites More sharing options...
chrisfowler99 Posted February 19, 2009 Author Share Posted February 19, 2009 I also guess I could go a little taller on the refugium one (assuming a center return) 14-15 inches, maybe? Quote Link to comment Share on other sites More sharing options...
Entropy Posted February 19, 2009 Share Posted February 19, 2009 I also guess I could go a little taller on the refugium one (assuming a center return)14-15 inches, maybe? You want as much water volume in the sump as possible, while being able to hold every drop if the power goes out, while keeping all your chambers as close to even as possible. The reasons are pretty obvious, but most of the designs I see usually fail at least one of those goals. The biggest mistakes I see are return chamber volume being to small, the refuge chamber being so much higher than the return chamber that the water spilling into the return chamber cause bubbles, and finally the sump just being to small all together. Along those lines I think the best setup is the refuge chamber feeding the drain chamber and then the drain chamber feeding the return chamber. This way you can set the refuge wall as high as you want and you don't have to worry about bubbles getting into the return chamber since they have to get through your bubble trap. You still have to worry about noise in this setup if the refuge is a lot higher than the drain chamber, but that is a standard risk on any sump model. Anyway I have rambled enough and probably didn't help much, but maybe I have offered something to think about. Quote Link to comment Share on other sites More sharing options...
caferacermike Posted February 19, 2009 Share Posted February 19, 2009 Best bet is to figure out the amount of water MIGHT backfeed into the sump. I use 4" of tank measurement to calculate the space needed in my sump to catch extra water. I divide my length x width x height by 231 to calculate gallons. So if my 75 gallon tank is 48"L x 18"W and I want to contain 4" in my sump= 3,456 cubic inches divided by 231= 14.96 or 15g of tank volume to be safe. Being that your sump will happen to be exactly half that amount I'd say run your baffles at 8-9" to be on the safe side. I only ever get about 2" of back siphoned water in my sump but be it that day that I'm not home and I've lost power, it would be that day when a snail or something pushed my return line deeper into the tank. I'm all about insurance, not so much wet floors. If you make your baffles 12" tall then let's do the math. 30x12x6=2,60 CI divided by 231= 9.4g of water in holding capacity. This is exactly 2.5" of your 75g tank's capacity. If you can guarantee that you'll only ever see 2" of water or less in the event of a power failure then feel free to run 12" of baffle. I wouldn't. I'd play it safe at 8". Quote Link to comment Share on other sites More sharing options...
Cool Breeze Posted February 19, 2009 Share Posted February 19, 2009 I second the notion that wet floors suck. Especially when they are carpet. Quote Link to comment Share on other sites More sharing options...
caferacermike Posted February 19, 2009 Share Posted February 19, 2009 Just felt like playing numbers for a bit. As another reference I'll compare the values of my own designed and built sump for my 400g tank. My tank's dimensions would equal 84x30x4= 10,080CI/231= 43.63 gallons of back siphon. My sump's overall dimensions are 60x24x16= 23,040Ci/231= 99.7 gallons I have the sump divided at 10", this leaves 6" space available. Let's do the math 60x24x6= 8,640 CI .Just shy of the 10,800CI from the above 4" of siphon. In gallons this translates to 37.4g. You can see I'm about 5g shy of my ideal goal. This does not concern me much for 2 reasons. First is that I have already calculated the speed of water through my sump and know that my return chamber that leads to my external pump will always be lower than my main 2 chambers. It will only have about 6" of water in it at any time. The chamber is 12x24x16 total volume The second reason is that 4" is plenty of insurance with lots of room to play with without getting wet floors. The math is First 2 chambers while operating leaves a volume of 48x24x6= 6,912 CI The return chamber in operation leaves a volume of 12x24x10= 2,880CI Together that is 9,792 CI /231= 42.38g of available space. Exactly enough. It's just all in how you do your math. Quote Link to comment Share on other sites More sharing options...
chrisfowler99 Posted February 20, 2009 Author Share Posted February 20, 2009 I actually ran the math too... My overflow is set 1" below the top of my tank, so if the tank was full to the top and then drained to the sump without return it would need ton contain 3.74 gallons. At 30x18, I need 2.34" of room to contain 3.74 gallons. I should have 6" over the baffles between the skimmer area and the return area. Going 14" at the refugium, which takes some of that space away (no exact measurement there as I haven't placed the wall yet), leaving only 4" there, still more than the 2.34" needed. Should be plenty...provided my overflow barrier isn't leaking, at which point all bets are off. Quote Link to comment Share on other sites More sharing options...
chrisfowler99 Posted February 20, 2009 Author Share Posted February 20, 2009 I went and ordered the baffles today at about...4:30. The woman that took my order seemed very apologetic that they would be ready until... tomorrow afternoon. Quote Link to comment Share on other sites More sharing options...
caferacermike Posted February 20, 2009 Share Posted February 20, 2009 I actually ran the math too...My overflow is set 1" below the top of my tank, so if the tank was full to the top and then drained to the sump without return it would need ton contain 3.74 gallons. At 30x18, I need 2.34" of room to contain 3.74 gallons. I should have 6" over the baffles between the skimmer area and the return area. Going 14" at the refugium, which takes some of that space away (no exact measurement there as I haven't placed the wall yet), leaving only 4" there, still more than the 2.34" needed. Should be plenty...provided my overflow barrier isn't leaking, at which point all bets are off. Ah but what happens when you need to put your hand all the way into the bottom of the sump to repair a skimmer or pull that snail off the pump intake that got stuck there? Yeah I like space. Quote Link to comment Share on other sites More sharing options...
Beretta Posted February 20, 2009 Share Posted February 20, 2009 Space is good, especially when your ato decides to dump all its water into your sump at one time because the float got stuck. Better to have excess space than not enough. My sump is large enough to accommodate a power outage and 5 extra gallons of ato water and not overflow. Quote Link to comment Share on other sites More sharing options...
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