Dosing Pumps for Daily Water Changing?

[Ryan S]

So... I was checking out this guy's 150g Automated SPS build on RC, and he does something I haven't seen before, nor thought of before. He uses dosers, like this one from BRS, to change his water on a daily basis, in small amounts.

 

IE. He has 2 jugs for each of the dosers. Lets say he has 5g jugs. One of them is full of fresh 1.025 saltwater; the other jug is empty. He runs the dosers for 60 minutes each per day. (50ml/min * 60min=3000ml/day or 0.8 gallons). Every week the fresh saltwater jug is empty, and the dirty one is full. He dumps the old, refills the new, and it does daily water changes everyday again. (Obviously, the bigger the jugs available the better; but this would work on a smaller scale for smaller total volume tanks too).

 

Any problems with such a system? It's a pretty simple semi-automated daily water change setup. Would removing such a small amount everyday be as effective as 20% tank volume bi-weekly? Never thought to use dosers in such a fashion, but seems interesting to me.

[BowieReefer84]

Want a good read...

 

http://reefkeeping.c...0/rhf/index.php

 

quote you may like,

 

"Continuous water changes: Continuous water changes, despite their name, are not necessarily performed every minute of every day. The distinguishing feature of these changes is that water is added at the same time that it is removed. The actual rate of addition can be high or low. Reef aquarists (myself included) most often perform these types of water changes with two matched pumps, one that removes the old water and one that adds the new water. Often these pumps are part of the same mechanism (such as two sets of tubing on a peristaltic pump or two heads on a diaphragm pump), but that is not a requirement. I use a dual head diaphragm pump capable of a maximum of 30 gallons per day for each head (a Reef Filler pump from Champion Lighting). In my setup, once I have a 44-gallon trash can full of new salt water, all I do to perform a 44 gallon or smaller water change is plug in the pump. The wastewater is sent down the drain. Sometimes I change 44 gallons in one shot, taking about a day and a half. Sometimes I pump for a few hours at a time, and then wait for a few days.

 

These changes are slightly less efficient than single batch water changes of the same total volume. A continuous water change of 30% exactly matches one batch 26% water change. As with very small batch water changes, these have the advantage of neither stressing the organisms (assuming the change is done reasonably slowly), nor altering the water level in the aquarium. The ease of doing such changes automatically also makes it far more likely that busy or lazy aquarists will actually do them."

 

 

Edited July 23, 2012 by BowieReefer84

[Ryan S]

Great read. Never even knew this was a water change method. I've always planned on the 2 large barrel system like the one bankyf just sold. You have a pump on it; open a valve to drain 50g; then close it and open another valve to pump 50g of fresh water into the system.

 

This alternative, I think I like even more. One dosing pump goes from the tank to a drain. And you have a single barrel with fresh saltwater (ideally as large a container as you can get). Change 40%/month automatically. No valves, switches, nothing. Just refill the saltwater jug when it gets empty... That's the type of automation that I like.

 

So if you had a 200g tank, you'd want to change 80g/month. Grab one of these bad boys, say the 100g for $140, and change 2.6g/day dosing. Just fill it up one day a month, add salt, done...

Edited July 23, 2012 by Ryan S

[Chad]

That's basically the idea behind a Spectrapure Litermeter 3 setup, although it's a more purpose-built reliable system than just doesers.

 

It uses three pumps and a controller to continuously alternate between draining, filling, and an ATO function (at the volumes we are talking about - on the order of 10s of mls per pump on time, I think mine is 6.5 ml at a shot - the water change doesn't affect the ATO function).

 

I don't do continuous water changes... but I do change the water 150 times a day

 

A few years back (somewhere there is a build thread for the upgrade, but I don't know where it is off hand so I reposted the pictures below) I installed my auto water change system (a LM3 head unit and two water exchange modules). Pricey, however, this was hands down the single best aquarium related purchase I have ever made. Once a week I refill my holding tanks (which can be left for up to ~18 days), test salinity, and move on: 10% water changes every week without hardly thinking about it.

 

 

 

 

[Ryan S]

I love it Chad!

[DaveS]

My main hangup with doser based water changes was to ensure they were matched well enough so that there wouldn't be creep over time from one direction out paving the other. With evaporation and an ATO this could lead to a drift in tank salinity. Maybe the newer dosers address this?

[Chad]

^exactly the issue to which I was referring when I mentioned reliability.

 

The only way that I know of to handle the situation is 1) be able to have control of the pump to the seconds and 2) measure the time it takes to fill a volume with the plumbing in place. With the fine-tuned control and known flow rate, you can pretty much eliminate the pumps from causing a problem to the equation.

 

However, after using an AWC for a while now, I will tell you that drift is a problem and it occurs more due minor changes and laziness in the salt mix part of the process (i.e., my fault) than it does because of pumps being slightly off. I have the issue occasionally because I mix in the make-up containers and measure salinity hours (days? ) after adding water and salt.

 

Forcing myself to do at least a weekly test of both the DT and the new salt container has pretty much eliminated this problem for me.

 

Here is the thread I was talking about, btw.

 

(and 6.5 vs. 37!!! Huh, I need to verify my settings!)