Will two 1.5" lines be enough for a Dart (and related questions...)?

[20 20]

I've got a Dart pump I'm going to use as a closed loop pump on my 125 reef I'm setting up. It's got a 2" input, and I need to drill the back of the tank for the bulkheads. So, some questions...

1 - I could drill one hole for a 2 inch line, but was wondering if two 1.5 inch lines, connected to a 2 inch drain that goes to the Dart will be enough. The Dart is rated at 3600 gph at zero head, I figure it'll push around 2800 - 2900 the way I'm going to have it set up.

2 - If the two 1.5 inch lines will work, is my assumption that I would use a 1.5 inch bulkhead be correct? Like this one: http://www.drsfostersmith.com/produc...1&N=2004&Nty=1 The 1.5 inch bulkhead has an inside diameter of 1.5 inches at it's smallest, right?

3 - Is the only option to keep critters from getting into the line to use a strainer like this one? http://www.drsfostersmith.com/produc...pc=1&N=0&Nty=1 Are there any kind of flatter 'strainers', so it's not sticking into the tank so much?

Any opinions would be greatly appreciated!

[20 20]

Anyone have any ideas?

[conefree]

Are you saying two 1.5" drains-->T-->2" pump suction? If so you should be ok. That gives the equivalent of a 2.12" ID pipe. It is fairly simple math, but a lot to type. Just a simple comparison of pipe inner circular area.

As far as the bulkheads go, I would personally go with sch 80 bulkheads like those found here: http://www.savko.com/PartList.asp?pgid=2&ptid=5
they are quite a bit thicker and stronger. Just keep in mind that you need to drill a much larger hole than the 1.5" bulkhead you want to attach. A 1.5" sch 40 bulkhead takes about a 2 3/8" hole, whereas a 1.5" sch 80 bulkhead takes about a 2 5/8" hole.

For the strainers, those are pretty good. Ask around and see what other DIY'ers are doing. You could just glue gutter guard acrosss the bulkheads for a strainer, but that leaves limited surface area and is more easily clogged by somthing laying flat on the strainer. That is where the strainers you linked are slightly better, because they are less likely to be clogged because of their larger surface area and shape.

HTH

[HotHotHot]

Regarding the Tee, you can also put the tee on the inside of the tank and have a single 2" drain. Saves bulkheads(cost) and only a single hole in the glass. If you check my thread (little red house) you'll see an example of how I did it. Here is a direct link.

Tee

HTH
Ed

[20 20]

Originally posted by conefree
Are you saying two 1.5" drains-->T-->2" pump suction? If so you should be ok. That gives the equivalent of a 2.12" ID pipe. It is fairly simple math, but a lot to type. Just a simple comparison of pipe inner circular area.

Yep, that's what I'm thinking of doing. Thanks for the link to the bulkheads, stronger is better. And yes, this helps alot!

[20 20]

How tight are those bulkheads to the hole size specified? I'm asking, because as far as I can tell 2 5/8 inches works out to 66.675mm, and I can find a 65mm hole bit. Will that 1.675mm smaller hole cause the bulkhead to not fit?

[20 20]

Originally posted by HotHotHot
Regarding the Tee, you can also put the tee on the inside of the tank and have a single 2" drain. Saves bulkheads(cost) and only a single hole in the glass. If you check my thread (little red house) you'll see an example of how I did it. Here is a direct link.

Tee

HTH
Ed

I kinda like the tee idea, I'll have to think about that. But the same question about hole size exists, if a bulkhead is rated for a 3 1/4" hole, that works out to 82.55mm, and I can find a either an 80 or an 85mm hole bit. Would either of them work for that bulkhead?

[MCary]

One other thing to know. In a closed loop there is no head loss. The pressure entering the system equals the pressure need to exit the system so gravities affect is nullified. The only loss will be from friction pressure. Pipe walls and elbows, and restriction. You'll probably get over 3200 gph with your setup if it is a true closed loop.

Mike

[20 20]

Thanks for that info, I didn't know that! Good news!

Anyone know the answer to my question about drill bit sizes, from two posts above?

[MCary]

I don't personnally know. You definitely can't use too small of a bit. But there is a large rim around the bulkhead. You would need to be carefull tightening them because with the extra room you could move or squeeze out your gasket.

I assume you want to buy a cheaper bit on E-bay from Hong Kong. They have almost all sizes and you will probably happen on a 83 mm bit. But you can buy a 3.25 inch bit domestically, it just costs alot more.

http://www.technologylk.com/product_...product_ID=107

I got one from here and it only took a couple of days to arrive.

Mike

[20 20]

Yeah, I'm looking at the Hong Kong bits. I'm considering it a 'throw away', used to drill these two holes (or 1 hold, if I go with the 2" bulkhead), and I figured even a cheap bit for $16 (including shipping) would last for that.

[MCary]

Depending on the thickness of your glass, bits are ususally good for only 10-15 holes anyway. So they are all basically throw-aways. Getting the cheapest you can find is the smartest action. I recently order a bit from e-bay for a 1.5 inch bulkhead, I'll let you know how they work if it ever shows up.

Seems like 85 mm would be really close. (would work)

Mike

[tang_man_montreal]

My closed loop is set up with 2x 1.5" lines going to a 2" reducing Tee at the intake of the Dart pump. Works great.

MDM did however state that there is no difference in reducing the intake to 1.5", and now actually sell the pumps with the 2" to 1.5" reducing bushing.

Here's some pics of my closed loop, the intake pipes are black ABS, hard to see against the black metal stand, but they are there.

[20 20]

Thanks again for the info, everyone. I've decided to go with two 1.5" input lines/holes/bulkheads, connecting to a 2" pipe to go to the Dart. I've ordering the bulkheads, hole opening size needed is 2 3/8" to 2.5". I've ordered a 60mm hole bit, which corresponds to the 2 3/8" hole.

Hope it works!

[MCary]

Just remember that 2 3/8" hole is for a standard bulkhead. Heavy duty bulkheads require a 2 5/8" hole.

Mike

[20 20]

Yep, I got the standard. Don't plan on yankin' on the plumbing much.

Famous last words, eh?