Iwaki pump plumbing question

[Fishbreath]

I would like to replace my internal pump with an external pump. Lots of good pump suggestions on this forum and I settled on the Iwaki MD30RLXT. Problem is it has a 1-inch output fitting and my return plumbing is 3/4-inch. Can I use an adapter? I'd like to keep the flow between 700 and 900 GPH and I'm also wondering if the additional backpressure from the adapter would raise the noise level of the pump. A reply from anyone with a similar experience would be appreciated. Thanks

 

[Len]

The RLXT models shouldn't be restricted. It can be done but Iwaki says it'll stress the motor; it should be a little more noisy and possibly more hot. I'm confident it'll work, but I don't know what effects it'll have on the pump's efficiency or reliablity. Perhaps trade it for a 30RLT model (they're 3/4") or T the return (1"x3/4"x3/4") and run two outputs.

 

[tangir1]

Actually backpressure will make the pump more quiet, if I recall my experience correctly...

Anyway, you will need a 40RLT to get that flow thru a 3/4. Or you can compromise with about 500 gph and get a 30RLT as Len suggested. With a 30RLXT, you going to get much less than 500 gph with a 3/4 opening due to the design of the impeller.

 

[tangir1]

Looking at the following chart, seem like you maybe able to get away with the 30RLXT if the head due to the 3/4 fitting is less than 10 feet... where the 30RLXT intercept with the 40RLT

or 18 feet where the 30RLXT intercept with the 30RLT

 

[liquid]

Check out http://www.reefs.org/library/pumps and http://www.reefs.org/pumps/

Shane

 

[Len]

My Iwakis have higher pitched, more audible noise when there is restriction in their outputs.

 

[Fishbreath]

Thanks everyone for the replies. I don't think I want to restrict the output if doing so could affect the pump's operation and reliability. Sounds like if I go with the MD30RLXT I should change out the 3/4-inch plumbing. I actually have an opportunity to do this since I'm moving the tank in about 6 weeks. So, next dumb question... how does one enlarge the holes in an acrylic tank for larger plumbing? Most hole drilling tools I've seen are designed to start from scratch with no existing hole. Anyone done this?

 

[Juck]

I've enlarged a hole on a glass tank with just a dremel and a grinding bit,, worked fine but I went real slow. This should work fine on an acrylic tank too,, just don't rush it.

 

[tangir1]

I used to enlarge a hole on an acrylic tank by using a piece of scrap wood for the pivot hole. Use a clamp to hold the wood in place (can be tricky to do since the tank is a box, and becareful with that clamp! Oh, no, a big scratch! ). Then you use a hole saw bit (with center drill bit) to drill like it is a virgin acrylic. Once the circular channel is created, you can remove the center bit and the wood to continue drilling thru the acrylic. The end result is a lot better than using a dremel

 

[Juck]

The end result is exactly the same,,, a bigger hole.

 

[tangir1]

It is not that big deal with bulkhead since it give you a bit of room for "un-roundness," but for amatuar DIYer like me, I prefer to make a hole that makes me feel good (but you never see the ugly job anyway :?)