Water changer issue with Stenner pump...

[sn4265]

I have setup a dual head Stenner pump to handle water changes for me, but unfortunately I have not been able to automate the process as of yet because of different flow rates. That said, the Stenner pump is doing a fantastic job and water changes are dramatically easier and less likely to disturb the tank occupants as well as make a mess. Plus, I am saving a TON of time by having the process/system setup. Let me first describe the system in a bit of detail.

The water making/storage station is in the laundry room and consists of a 50 gal food grade drum (had green chili peppers originally). This drum sits on the floor directly below my 6 stage RODI system from BRS. The tank is in the dining room about 25' away and I have run the water lines up thru the attic and walls such that they are completely out of site and out of mind. One of these lines is pumping FSW from the drum into the tank while the other pulls old tank water from the sump into either a bucket in the laundry room or down the laundry drain. The pump is currently controlled via a 50' extension cord that goes from my Apex thru the same holes in the walls as the water lines.

Right now the problem is that the Stenner is pulling water out of the tank faster then it's pumping water into the tank, and by a pretty significant amount. Here is my current process to accommodate the different flow rates:

1. Turn off the ATO
2. Put drain/out water line into actual water in the sump in the section that drains from the tank.
3. Turn on the Stenner via the Apex for about 3 hours to change 5 gallons.
4. After about 3 hours, pull the drain/out water line from the water and leave it just sucking air so I'm no longer removing any water from the sump.
5. After about 20 minutes, the Stenner will have made up the difference in flow rates by only pumping water into the tank.
6. Turn off the Stenner and turn back on the ATO.

Suffice to say, this is immensely easier than the old method of hauling buckets around. I love that I can kick this off in about 30 seconds and the cleanup time is less then that. However, I would love to get the flowrates synchronized such that I could actually automate this to happen for a set amount of time daily.

I have tried switching which head pumps into and out of the tank and this didn't really make any difference. My next thought is to install an airline valve in the drain/out line so I could throttle down the flowrate from that line to get it matched up to the FSW line flowrate. I thought that these pumps were designed to pump the same volume but that just doesn't seem to be the case for me.

Anyone else having similar issues with the Stenner dual head pumps? Any thoughts or other suggestions on how to tackle this issue? Thanks in advance.

[Philly guy]

I am assuming that your sump is directly below your tank. If it is then you have a difference in height between the two which will affect the flow rates. If the tank and sump are in different rooms then you are definitely going to have different flow rates because of the distance that the water is being pumped, pulled. Try putting both the supply and return line in the sump at opposite ends to minimize the amount of new water that is being drawn off. By doing this you eliminate the distance and head loss issue and you also should not have to turn your ATO off to do the water change. As the water is entering and exiting at the same rate.

Also there is a large thread on automatic water changes on the FMAS club forum (Florida Marine Aquarium Society). Hope this helps.

[sn4265]

Sorry if this wasn't unclear. Both the in and out are in the sump with old water coming out of the sump from the section that the tank drains into and then the new water pumping into the fuge section at the other end of the sump. This pumps the new FSW as far as possible away from where it could be removed as it would have to go from the fuge up into the DT and then back down to the drain section of the sump where the skimmer is located.

I'll see what I might be able to find in the FMAS forum.

[tkeracer619]

When I recommend dual head peristaltic pumps for auto water change systems I always recommend that one of your pump heads (the one with the most head pressure) has adjustable occlusion (tube pinch).

While not ideal you can put a valve on the output of the fast flowing line and restrict it until you balance the system. Head pressure does effect peristaltic pumps, just not as dramatic as centrifugal pumps.

I would not run this system continuously unless you have a salinity probe. It is best to do it for an hour or two a day IME.

[sn4265]

Thanks for the advice.

So you would recommend putting the flow restriction on the discharge of the fast flowing line rather than on the suction side? I hadn't thought of that.

I never intended to run this system continuously. I would probably just run it maybe 3 times per day for 15 minutes or so each time. This should give me about a gallon per day water change which is what I'm looking for at this point as that would be about 20% per month I think.

[tkeracer619]

Sounds good. Yup, while not optimal it will work. The only reason I say the output is because the tubing works better in pressure vs vacuum.

[CHSUB]

I put my Stenner half way between my DT and water vat and it moves the same amount of water on both sides. maybe i'm just lucky, but that's why i centered the pump between the two.

[sn4265]

Unfortunately for me half way between would be in the attic and I'd really like to have easier access to the pump.

[iammrhappy]

did you ever resolve this issue? I have reverse of your problem. The stenner dual head is bringing in more water than it is taking out. First day of use so I'll need to see if tubes just need to be broken in or system just needs to balance itself out.