Auto/Continuous Water Change Idea

cpllongjk · Mar 14, 2016

Can someone help me flesh this idea out.

The idea is to use my currently float valve setup to top off Fresh Water and add a Salt Water reservoir in order to do auto/continuous water changes.

I have never liked the idea of using two pumps for auto/continuous water changes; if one pump is faster than another it could lead to big changes in salinity.

Please look at the simple drawing below and tell me what you think.

Here is a picture of my current setup.

A "Y" valve would be added before the float valve in the sump in order to switch between fresh water and salt water. My biggest issue with this method is the way to stop the flow of Fresh Water from the FW reservoir so that the salt water will replace any water taken out by the dosing/metering pump. I would also need a way to stop the salt water when the FW top off was engaged.

Using this method would allow for 100% reliability and accuracy that whatever water is taken out of the tank is replaced with salt water and no fresh water.

Am I overthinking this? Anyone use anything like this or should I just use two dosing pumps and try my best to get them in sync?

cilyjr · Mar 14, 2016

Replied to your post on the other forum but I'll post here as well. I think an easier way is to buy a dual head parastaltic pump that runs both heads off 1 motor (see pictures below) that can be louder but you are only pumping a few times daily.

Tube length and head pump can vary amounts a bit but I've been using this for years now and I've not had salinity issues

cpllongjk · Mar 14, 2016

How much is a setup like this?

cilyjr · Mar 14, 2016

I bought the pump used for 75 bucks. Then it's just tubing and fittings for airline tubing to attach to the rubber tubing in the pump head

Arkonen · Mar 31, 2016

I second what cilyjr mentioned. I use a Stenner brand dual head stepper motor to do 2 gallons a day on my system automatically. My Apex turns it on/off for the required time. No salinity issues so far in the last year.

cb684 · Mar 31, 2016

cpllongjk said:
I have never liked the idea of using two pumps for auto/continuous water changes; if one pump is faster than another it could lead to big changes in salinity.

So, I use to think the same, but with a water change of 1% a day (which is usually enough) even if one of the pumps stopped working it would take enough time that you would be able to find out before a bigger problem happened. Also, the changes are very slow so variations won't have such a big impact.
Two-head pumps will further minimize this problem. So, at this point, I use a setup like this.