Ok, the 3rd pump showed up tonight, and I tried a ton of different things…
The short answer is… all 3 pumps worked the same. They were silent when run with zero back pressure. They all whine when hooked up to the RedSea Reefer 425 return plumbing. Some adjustments made the noise a bit more tolerable (a little quieter, and deeper in pitch). But its still there.
The longer answer...
The 3rd pump showed up tonight, and at first I put it in place of the previous one, running through my manifold at about 50%. It was considerably louder than either of the first two. So much so that it was clear that something wasn’t right. There was a loud rattling noise, you can hear it
here and
here.
I knew the Ecotech support folks would ask me to take the pump apart, and send them pics/videos of the noisy 3rd pump as they did the first two, so I went ahead and did that. I noticed a little “grit” on the magnet, so I wiped the whole thing down, rinsed it off, and put it back together. And, now it sounded just like the first two, as you can
hear here. I should also note that I added a silicone pad under the pump to eliminate any noise from vibration against the bottom.
So, if you get a new
really loud M1, start by cleaning it.
At this point, pump number 3 was behaving just like the first two, so my conclusion is that the pumps weren’t “broken”. Chances of all 3 not functioning as designed while functioning identically seems slim. So I decided to experiment to see what part of my system was making this pump loud when it works silently for others.
I tried the following tests:
- Running the pump from the skimmer chamber with no manifold. I used soft tubing to connect directly to the RSR return plumbing. Still loud. Click here to see this test.
- Running the pump from the return pump chamber with no manifold. Still loud. Click here to see this test.
- Running the pump through ~10’ of 5/8” ID tubing back into the sump. Click here to see this test. This one surprised me. I knew by this point that back pressure was making the pump loud, but I didn’t think there would be enough back pressure from some tubing. Yes, the tubing wasn’t perfectly smooth since the 5/8” tubing was stuck inside ~18” of 3/4" ID tubing, but still… As you can hear, this caused the pump to strain enough to make noticeable noise.
- So, next I tried running the pump just through the ~18” of 3/4" ID tubing. At 50% it was pretty quiet. At 100% it made some noise, but not too bad. Click here to see this test.
- Swapping between the stock return nozzle and the loc-line splitter return nozzle. When I took a look at the tiny diameter of the loc-line splitter segment, it was clear that this was also adding back pressure. To prove this out, I put the stock nozzle in place, and dialed in the overflow dial until the overflow was running optimally. Then I switched in the loc-line splitter and the water level in the sump started to drop. Clearly less water was coming through the splitter.
So, my conclusion is that these pumps get noisy with back pressure. Just running the pump with no plumbing and blocking the outlet a little with my fingers demonstrated this easily. And, while I love almost everything about this tank, the return elbow (see below) is clearly a weak link. Look at the diameter relative to the rest of the plumbing! My guess is that this is what’s causing the majority of the back pressure when I run the pump hooked directly to the return plumbing. Unfortunately, this is a custom fitting, and I don’t know of an easy way to replace it. And I still don’t know why this isn’t causing issues for others running RedSea Reefers with this pump.
At this point, I think I’ll have to live with this. I’m not sure I can return a pump that’s functioning “normally”, but operates loudly in my Reefer. And even if I could return it, I don’t know what I’d replace it with.
