Another 240 Gal Sump question.

[VFX_Bishop]

Hey guys, this topic has been beaten to death, but in looking around I haven't been able to find an answer that made me happy. I just bought a 240 gallon acrylic tank (8x2x2) and I'm in the process of planning out the filtration side of things for it. The tank is pre-drilled with two 3/4" NPT holes in the bottom and a single 1/2" NPT hole which I imagine was originally a return since I can't imagine why you'd make one hole smaller than the other two. There are also a pair of holes in the top of the tank near the side panel which will fit 3/4" SCH 40 PVC pipe, though I was planning on using those holes to run wires to Koralia pumps.

The 1/2" NPT hole is troublesome as it is threaded (they're all threaded actually) and I can't get a nipple long enough to protrude all the way through the tank to get enough to comfortably screw a 1-1/4" bushing onto with a rubber washer and still have something to work with on the outside of the tank. The 3/4" NPT holes seem to be okay and I've made "bulkheads" that I hope will work using a 1-1/4" reducing threaded bushing, a rubber washer, 3/4" all thread nipple, and a 1" reducing threaded bushing on the outside. I'm not sure if I should just use a dremmel and make the 1/2" hole a little wider and just slide a 1/2" NPT nipple that's long enough, but unthreaded, through and wrench the whole thing down or not. I can't see why it would be a "bad thing" since what would be sealing the system would be the washer and not the threads/teflon tape. But I'm a little hesitant to just start modding a tank that's 5 times bigger than anything else I've ever owned in a material I have no experience with.

I've also mostly decided that I'll be going with the old tried-and-true DIY sump setup with a pair of Mag 18's for returns but that brings me to my second problem. I'm aware that I'll lose flow from the pumps as head increases and that they'll be closer to a combined 2400 gph once all is said and done. I also realize that I'm going to need to drill more holes in the tank to be able to process that much water flowing through the tank. What I'm not sure of is how exactly to do that. I can expect at best around 900-1000 gph coming from what's already drilled in the tank, but I recall someone saying that using a tank the way it was drilled can be more trouble than it's worth.

I mean I get that you go out and buy a hole saw the size that's appropriate for your bulkhead, cut a hole and then plumb it up. What I'm not sure about is exactly how to figure out where the bulkhead should be placed relative to the top of the tank I guess. Are there advantages to setting things up one way vs. another? As I write this I have three stand pipes ready to go which are about 21-22" high in the tank and have gutter mesh to act as a strainer to keep fish out. I really am a newb when it comes to actually owning a large tank and I've never drilled a tank before either. I've always owned glass and it would be simple if this were a glass tank to just buy a couple of HOB overflows and plumb everything up that way since it's non-invasive.

So is it worth working with the fittings that are already installed in the tank or should I seal them up and just punch new holes the size and location that I want/need to overflow my pumps of choice? Is there a more effective way to seal up those existing holes if I'm not going to use them?

 

[SpeshulEd]

I think the answer to a lot of your questions is bulkheads.

If you want to plug holes, you can use bulkheads and put the plug in the bulkhead. I would also use real bulkheads over making your own. They're relatively cheap online and can be found a number of places. I think I've gotten them from drsfostersmith.com and glass-holes.com in the past.

Before plugging current holes and drilling new ones, I think I'd just use what you have...and maybe drill them bigger for more flow. With acrylic tanks, all you need is a normal hole saw, no special bits like when you drill glass.

On my 210, I have two 1" (I think they're 1") holes for overflows/drains and two 3/4" holes for returns. I have the two overflows draining to a sump, the sump returns to one return. I then used an fx5, but the fx5 sucked faster than the overflow could handle, so I had to use its own which I ran over the back. The fx5 returns through the other hole in the bottom rather than running that over the back of the tank. Here's a photo, its kind of old.

I have plenty of flow in the tank...I hardly even gravel vac when I clean because everything gets sucked away by the filters.

 

[CA-Delta]

+1 for buying bulkhead fittings.
You definitely are not limited to using the existing holes.
The cool thing about acrylic is you can poke a hole anywhere you want to.
Personally, I would decide on a filtration design and then see if any or all of the existing holes can be utilized.
If they can fine, if they can't, install a threaded bulkhead and a plug.

My 240 acrylic had a 1/2" hole drilled in the botton that I wound up using to supply my airstones.

 

[VFX_Bishop]

Well if I'm going to get bulkheads I'm going to have to drill the tank to install them unless I get 1/8" NPT and 1/4" NPT bulkheads for the 1/2" and 3/4" holes respectively. I'd be willing to drill all three holes in the bottom to accommodate a 1/2" NPT bulkhead which needs a 1-1/8" hole and there are already two 1.05" holes in the tank. I don't know that I can go much larger since where the tank is drilled there are reinforcement acrylic plates which I'm a little nervous about getting too close to the edge of since the manufacturer probably put them there for a reason.

 

[SpeshulEd]

Yeah, I'd try to stay away from the reinforcement plates, but go as big as you can otherwise.

When it comes to moving water, bigger always seems to be better.

 

[VFX_Bishop]

Okay. I'm going to be making plans this evening after I get done with work on how I want my filter system to be setup and I'm curious if there's a certain size sump that I should go for or just "as big as I can get under the tank". Either way I'm limited to having it only be 13" deep and about as wide which means it'll be a long skinny thing under the tank of the bracing I'm doing.

The stand itself is 2x6 beams with 4x4 posts and a deck made of 2x6's and 2x4's. I'll post plans of that as well this evening and see what you guys think.

 

[SpeshulEd]

Just make sure the sump is big enough to hold the water that drains out of your tank when the pump is off.

If not, you might have a wet floor if the power goes out.

 

[VFX_Bishop]

I am aware of that little problem, but I appreciate you reminding me!

Based on the dimensions of the stand and what I'll be able to fit under there it looks like a 33 long will be my "only" option for a sump unless I make a chambered sump system with a lot of smaller tanks/rubbermaids with siphon tubes or bulkheads linking them together. Plans will be up soon.

 

[Egon]

The stand itself is 2x6 beams with 4x4 posts and a deck made of 2x6's and 2x4's. I'll post plans of that as well this evening and see what you guys think.

Crap that's a beefy stand! If you haven't built the stand already look into using 2X4's. It will save you $$$ to spend on stocking

If ya already built the stand no big deal. Stronger never hurt anything.

 

[VFX_Bishop]

Well I already have all the wood cut and ready to go. I wanted to "over build" it since I didn't know how much weight the stand could carry and I took the plans from a 220 gal 7 foot tank that a guy had posted using a similar method and expanded it to 8 feet and added an additional iteration of posts and cross members just to make me feel better. My dad's adage of "When in doubt, build it stout." came to mind when I was designing this. The stand is still a pile of wood laying on the floor and can become whatever really.

Here's the plan for the stand.


Here's my idea for plumbing. but I don't know about how "easy" this will be to work with since I'll have no real room to work. I'm considering not installing the lower center two cross members to allow me the room to drop the tank in the middle and call it a project.


If I do drop the tank in the middle without the two lower cross pieces then I'll have about 9" of room above the sump which would be a lot nicer to work with than the 1" I have as planned. The wood being used for this is Doug Fir if that makes a difference to anyone.


On the topic of stocking. This will be the future home for my 5 current Clown Loaches who will be getting 10 or so more buddies now that I have the physical space to have a tank larger than a 55 in my home. Joining them are a school of Giant Danios and a Pictus Cat.

Opinions?