View Full Version : Mag pumps external
04/18/2003, 11:27 AM
I noticed in your printed catalog that you say mag pumps are not recommended for external use with salt water applications. Can you elaborate on this? The reason I ask is that I am using a mag 3 for re-circulation of my calcium reactor. The pump has gotten real noisy with time, so I ordered a new impellar. Will know next week if it works, but was wondering if the same thing will happen in short time.
04/18/2003, 02:53 PM
Basically, we are erring on the safe side. We have seen and heard of many premature burnouts for the pump when used externally. Naturally, the pump is going to run cooler when submersed since water is a much better conductor of heat/cold than air. Also, we have seen external seals wearing out over time. Used submersed, that is not such a big issue as the water will leak into water. Used externally, the user would need to silicone and waterproof the unit when the leaking starts or replace the pump.
That said, the mag drive pumps are an excellent pump and a great many of our customer use them externally with good results. We just want our customers make an informed decision.
05/03/2003, 11:32 AM
I use two external mag 7's. They do run hot and I have a fan blowing on them. I'd rather have that heat dissipate into the air rather than in my water. There is a little salt creep out of them, so they aren't the best used externally, but they work. Very cheap impellers.
In the short run, they are economical. I run two pumps, however. I got two set up as a backup in case one fails, but I'm thinking this wasn't the best idea. I'm using 1.5 amps on each pump. For big flow operations if you want an external pump, I'd look somewhere else (aside from mag, not aside from marine depot). They have some nice external pumps that use low power. The dolphin amp masters that marine deopt sells are low amps and good external pumps. This is just one pump I'm considering buying from Marine Depot soon.
It should also be noted that mags can't be hard plumbed from what I hear. Their casing isn't strong enough to withstand the pressure and will crack.
Good luck shopping.
Old Yeller Tang
05/03/2003, 11:56 AM
They're not recommended externally because they have a tendency to leak because they don't have a sufficient o-ring seal in some of them. I bought a Mag 2 for my reactor and it leaked right off the bat. I had to get a bigger rubber o-ring to give it a better seal. When you open it up to replace the gasket, you can easily see why it would leak as there is an exposed area in the seal compartment that needs a tight seal to prevent leaks.
05/04/2003, 12:33 AM
I definately knew that a leak was a possibilty. As a precaution, I put a plastic shoe box down and set the mag drives inside the box. There was some salt buildup in the boxes over time also. As I said before, it's the heat and not the leaking that's a problem. Yes, the heat will burn out the motors sooner and placing them in my tank will dissipate the heat a bit, but I can't have ALL of that heat going into my water. The tank is already 78f.
It is interesting that you can replace the gasket seal. I never thought of that before. Do you have any suggestions as to how I would go about doing this?
I mean... I'm looking for as simple directions as driving down to home depot and getting the right size gasket seal. I really don't know. Until I replace the pumps, this would be a good idea.
(Even if it weren't for the heat or the leaky gaskets, I'll still save money going with a 1 amp pump rather than 3 amps total... I think mag drive makes a good pump for the price. When I was first looking at prices for my DIY sump, spending over $200 on a pump was rediculous! After working so hard on my tank though has justified any such costs... whether it be lighting, filtration or anything else... what ever is best for the tank :D )
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