Using/modifying freshwater pumps for saltwater

[Jims_Reefing]

Hi everyone, so I've set up a little betta tank as an amphipod culture tank but the powerhead that the internal filter comes with is obviously designed for freshwater; I was wondering, is it really such an issue to use a pump that likely has a stainless steel shaft for marine purposes? The pumps have to be sealed completely or else they would also fail in freshwater should their electronics come into contact with water so I highly doubt there would be internal problems; are the resins used to seal them less stable in saltwater? I also have a hydor pico mini internal filter, which is also designed for freshwater, that I'm using for additional flow in the tank and to house a small amount of carbon (I've had a corallimorph in for a short while to act as a cycle canary). I know it's regarded as a cardinal sin but wouldn't the corrosion both take a long time and probably not release much that isn't already found in many coral additives into the water? Because of the low performance required in my instance, I really wouldn't care if I had to replace a $20 pump every so often or just let it run until it dies then modify the filter to hold something more appropriate.

This also got me thinking, why wouldn't I be able to retrofit the pumps with ceramic shafts in order to circumvent this problem? Are the magnets that drive the impeller also prone to corrosion? Could these also be replaced? Looking forward to hearing anybody's experiences with pumps clapping out or corrosion issues, and any stories of such modifications you may have!

Here's the tank at time of writing, no amphipods added yet as I'm still waiting for the shipment to arrive but I've got a bit of chaeto and some live rock in there to help them feel at home.

 

[shwareefer]

Hi everyone, so I've set up a little betta tank as an amphipod culture tank but the powerhead that the internal filter comes with is obviously designed for freshwater; I was wondering, is it really such an issue to use a pump that likely has a stainless steel shaft for marine purposes? The pumps have to be sealed completely or else they would also fail in freshwater should their electronics come into contact with water so I highly doubt there would be internal problems; are the resins used to seal them less stable in saltwater? I also have a hydor pico mini internal filter, which is also designed for freshwater, that I'm using for additional flow in the tank and to house a small amount of carbon (I've had a corallimorph in for a short while to act as a cycle canary). I know it's regarded as a cardinal sin but wouldn't the corrosion both take a long time and probably not release much that isn't already found in many coral additives into the water? Because of the low performance required in my instance, I really wouldn't care if I had to replace a $20 pump every so often or just let it run until it dies then modify the filter to hold something more appropriate.

This also got me thinking, why wouldn't I be able to retrofit the pumps with ceramic shafts in order to circumvent this problem? Are the magnets that drive the impeller also prone to corrosion? Could these also be replaced? Looking forward to hearing anybody's experiences with pumps clapping out or corrosion issues, and any stories of such modifications you may have!

Here's the tank at time of writing, no amphipods added yet as I'm still waiting for the shipment to arrive but I've got a bit of chaeto and some live rock in there to help them feel at home.

People use fresh water pumps and filters on saltwater all the time. I'd just use them and check on them in a week to see if anything is corroding. I would guess the hydor filter would be fine. The powerhead's stainless shaft might corrode - saltwater usually uses titanium or ceramic.

 

[Jims_Reefing]

People use fresh water pumps and filters on saltwater all the time. I'd just use them and check on them in a week to see if anything is corroding. I would guess the hydor filter would be fine. The powerhead's stainless shaft might corrode - saltwater usually uses titanium or ceramic.

I suppose I'm primarily interested in the potential effects on such a small water volume, it's only a 10L tank. I didn't logically see anything wrong with it but the hysteria around corroding freshwater pumps abounds online and made me wonder if it was simply a "rust bad buy saltwater product because not freshwater" sort of argument or if they actually had some proven concept of why it shouldn't be done.

 

[laverda]

It just depends on what the shafts are made of. I have seen some that were steel of some type which will not last long and will contaminate the water with metals. Stainless will also do the same, but take much longer depending on the specific alloy.
You can replace most shafts if you can find an equalivent one in ceramic. That sounds easy, but I think you will not find that to be the case.