Sump baffle size

I would use 1/4" glass for my baffles....Also curious as to the size of your sump....  From experience 12" height on your baffles is to deep and I'm sure if your sump is average standard size 12" will be way to deep and will create issues for you down the road.  Speaking from experience; my sump is 4' L x 3'W x 22"H, and my baffles were 11" and they had to be cut down.....Just my .02

Id go with 1/4" as well in your case because of the width of the baffles. You could probably get away with 3/16" but glass is cheap in these thicknesses so why gamble over an extra few bucks. Thats my take on it.

I hear what your saying, but siphon breaks can clog and fail, but as long as your comfortable that's all that matters.  I for one even though my sump can hold 158 gallons don't want to run more than 10" of water.

I think it just depends on how you're using a siphon break and whether or not you rely 100% solely on that to prevent a flood.  As long as you don't flood your sump even after you block off the siphon hole then you should be good to go as far as making them as high as you want and still remain within the safe zone of no floods in a worst case scenario.

 

Similarly, that's pretty much how I've designed mine.  I do have some siphon breaks but incase they don't work my return outputs are high enough that I'm not in any danger of flood.  My sump is 16" high, baffles 12" high with 1-1/4" teeth.  So my water level sets just below 11" in my skimmer and fuge chamber and will run right around 9" in my return chamber.  Even with all of my backflow I won't flood the return chamber.  Only in the event of a catastrophic failure of multiple siphon holes will my water level ever rise about an inch over my baffles.  So I think I'm good as far as that goes (knock on wood).

I'm speaking a bit from experience and a bit of caution.....Again relying solely on siphon breaks can be disastrous...Another thing you want and should consider is type of skimmer you will be running.....12" water depth is way to deep for most skimmers to operate.  Which in turns means you have to elevate the skimmer on a stand.....In turn this takes away any clearance you have underneath the stand to get the skimmer cup off......

 

I'm not saying by any means your design is flawed or wouldn't work, but if you look at melevsreef.com which I like to refer people to since Mark has done (does) excellent work, but you never see a sump with baffles that tall.  Again not saying it can't or couldn't be done, but theoretically there isn't any need for it.....You always have to allow yourself extra headroom....Systems change over time.....

 

I understand what your saying about utilizing all space available, but I don't think your really gaining much if anything running a sump level that high.....Again I chose to run mine at 10" only after cutting them down, and that was more for the choice of being able to open my pump wide open if I choose or decide to opt to a bigger pump.  

 

I'm curious you never mentioned size of DT or return pump as well in your original post......

Funny thing....I was browsing last night over on RC and came across a thread you and Bean had about this subject on siphon breaks.........

 

Again only cautioning, but to be honest I never in the past 19yrs have never used siphon breaks.....I've never had a flood due to power outage as well.  I have had a flood due to tank failure.....So again depends again how much faith you have in your abilities or work.....I've used check valves and have never had issues as some will attest you will......Again comes down to personal preference.  

 

This new setup I am using siphon breaks, and (2) of my returns are submerged very deep....6" below the water surface.  I drilled large siphon breaks and get 4" of back flow.....Leaves me plenty of comfort zone as well.....

Ahhh, yeah...I remember that.  The guy had a problem with the idea that my entire return was essentially one big siphon break and felt the need to argue that siphon break holes were the devil.  Even though I agreed with him over and over that setting your returns in a safe position was the best way to go to avoid a flood.  I think he has issues with letting go.