Help calculating overflow and weir size

[adova]

I am designing a tank 72 x 20 x 30(h) that will be 3 sides visible out of 1/2" acrylic. I would like an external overflow to span the entire width of the one side and incorporate a BeanAnimal overflow.

Basic Tank Layout

I am trying to figure out the optimal sizes for 2 things:

1. How deep should the weir (toothless) be cut​

1. What is the best size for the overflow?​

Thanks in advance!

Shawn

 

[thejuggernaut]

According to this:

http://irrigation.wsu.edu/Content/Calculators/Water-Measurements/Rectangular-Contracted-Weir.php

A 20" weir at 2400 GPH will raise the water level above the over flow 3/4". You can plug in other numbers to find one that better fits your flow.

 

[Gorgok]

With the above in mind i would aim for a depth on the weir that your bracing doesn't get wet even with some wavy water movement. Keeping them clean otherwise will get really annoying. So with a 3/4 rise i think at least 1" on the weir is necessary, maybe more.

 

[adova]

sounds good - how did you come up with a 2400 GPH figure? Is that a fairly standard flow rate?

Any idea on the volume needs of the overflow? or does it even matter if the sump can handle the volume during poweroff?

 

[thejuggernaut]

Tank is about 185 gallons. Some people do small amounts of sump turn over but honestly I always tried to have atleast 10-15 times. Especially drawing from the short in. You'll need more flow to effectively surface skim

 

[woodnaquanut]

You might want to run your design by the acrylic tank thread. For a 30" tall tank 1/2" might be cutting it close. Also is there no cross brace?

There's a lot of controversy about turnover. Mostly 5x and 10x+ camps. Pick your camp and move in! I'm a card carrying member of the 5x camp.

 

[adova]

You might want to run your design by the acrylic tank thread. For a 30" tall tank 1/2" might be cutting it close. Also is there no cross brace?

That sketchup wasn't designed to be super accurate - more to help layout the stand and give a general feel. I plan to do at least one cross brace and maybe two into a once piece eurobrace.

Most of the feedback that I have seen about using 1/2" is that there may be some slight deflection, but I think I can live with that. Perhaps I could do 3/4" for the sides, though. They are going to take up almost a full sheet anyways and it would be worth the extra $200.

 

[adova]

Ugh - Just realized - 2 extra sheets. But that would be all 4 sides.

 

[Gorgok]

30" tall is also tall enough for my sleeves to get wet trying to pick up something off the sandbed. I have one tank like that and would not wish it again. If instead you sized it to be a sheet split in half... I realize that ~24" high would be a 20% loss in volume, but stacking stuff that high is tricky anyway.

 

[adova]

I know - I my current 240 is like that. It has been so long since it has been up that I sometimes forget the hassle of a deep tank. Some good food for thought - thanks!

 

[woodnaquanut]

30" tall is also tall enough for my sleeves to get wet trying to pick up something off the sandbed.

Good for you. At 24" I'm armpit damp. At 30" it would be time for snorkel gear!

 

[SGT_York]

I just plumbed my 180 in the same type of setup. Don't press the GPH due to the weir limit of 24" at 3/4" you will have significant intake into the overflow. Part of the aesthetics of a see through tank is the weir overflow limit. If you exceed 1500 GPH I'd bet you'll have a constant inflow of snails that won't be able to crawl out. I used a gyre on the opposite side which creates some wave action that impacts the weir water level and overflow water height, adds some air into the siphon on occasion. You may want to keep with the lower overflow probably about 7 inches to alleviate the air intake.

 

[adova]

SGT - Do you have a link to your build?

 

[SGT_York]

Not yet.

I was running a PanWorld 200 which was 3/4" above my overflow so I switched back to my PW 100 which isn't enough flow for my liking. I'm going to purchase a waveline??? DC pump and see how that works out.

 

[Mrramsey]

Not yet.

I was running a PanWorld 200 which was 3/4" above my overflow so I switched back to my PW 100 which isn't enough flow for my liking. I'm going to purchase a waveline??? DC pump and see how that works out.

Hey SGT - which waveline are you going to get? I am running a Sicce HF-10 on my 120g needless to say it's Waaaaaaayyyy to much pump. I am needing about 1100gph @ 8' of head.