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RC Blogs · 11/19/2011, 04:21 PM

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So, this weekend I hooked up the Litermeter III. The plan was to set it up to swap out 20 gallons of water per week, and top up with freshwater. It didn't quite turn out that way, and I suspect I've got the wrong pump (I bought an 'external pump' rather than a 'water-exchange unit'). I think I'll be able to do it though.

In the snapshot, the blue line is the freshwater, the red line is the new salt water, and the black line is the drain. I made 'shelves' by stringing some 2x4's between the legs, and secured the units to the shelves using some industrial-strength velcro. Even though the peristaltic pumps vibrate (quietly :) ) they're not coming off that shelf.

The nice thing about the LM3 is that it calibrates the dosage lines for you, and it turns out that my waste-water line can dump about 260 ml/min, but my saltwater-in line can only source about 160 ml/min. I guess the additional overhead of pumping up as well as along the 70' line causes an extra head loss, and therefore a lower pump rate. Still, because it's calibrated, I just tell both pumps to process 11 liters per day, and they'll run however long they need to, to make sure the same amount of water comes in as goes out. All very satisfying :)

So, I have it doing the water changes, but I need the water-exchange unit to do the automatic top-off thing, so that the pump stops adding water once the sump water-level reaches a certain height. I have a query in with Spectrapure to see if they have any advice as to how I can do it with what I have, else I'll have to swap one of the external pump units for a water-exchange unit. At the moment, I'm just topping off manually...

11/19/2011, 04:21 PM	#1
RC Blogs RSS Poster Robot Join Date: Nov 2011 Posts: 1,024	Ch,Ch,Ch,Chaaanges... Read in RC Blogs. So, this weekend I hooked up the Litermeter III. The plan was to set it up to swap out 20 gallons of water per week, and top up with freshwater. It didn't quite turn out that way, and I suspect I've got the wrong pump (I bought an 'external pump' rather than a 'water-exchange unit'). I think I'll be able to do it though. In the snapshot, the blue line is the freshwater, the red line is the new salt water, and the black line is the drain. I made 'shelves' by stringing some 2x4's between the legs, and secured the units to the shelves using some industrial-strength velcro. Even though the peristaltic pumps vibrate (quietly :) ) they're not coming off that shelf. The nice thing about the LM3 is that it calibrates the dosage lines for you, and it turns out that my waste-water line can dump about 260 ml/min, but my saltwater-in line can only source about 160 ml/min. I guess the additional overhead of pumping up as well as along the 70' line causes an extra head loss, and therefore a lower pump rate. Still, because it's calibrated, I just tell both pumps to process 11 liters per day, and they'll run however long they need to, to make sure the same amount of water comes in as goes out. All very satisfying :) So, I have it doing the water changes, but I need the water-exchange unit to do the automatic top-off thing, so that the pump stops adding water once the sump water-level reaches a certain height. I have a query in with Spectrapure to see if they have any advice as to how I can do it with what I have, else I'll have to swap one of the external pump units for a water-exchange unit. At the moment, I'm just topping off manually...