DIY Auto water change system idea - What do you think?

[lpsouth1978@msn.com]

I have been looking into an auto water change system for an upcoming 55 gallon build, and have not had any luck finding something affordable to do the trick. The commercially available systems are quite expensive, like $500 - $1000, and pretty bulky. This got me thinking about, and researching DIY systems, but they all seem to be overly complicated and not real fool proof.

Now for my idea:
(NOTE: This would probably not work on large tanks - Over ~90 gallons)

I figure "Why can't I use a dosing pump"? like the Kamoer on aquastyleonline.com - http://www.aquastyleonline.com/products/Kamoer-Aquarium-Dosing-Pump-System.html
In custom mode this pump can move up to 9,999mL per day. That is about 2.5 gallons per day, more than I will need. I figure that if I want to change 60% a month I would need to change 1.1 gallons a day.

The basic idea is that the system would do 18 very small water changes each day. Pump 1 would run for 10 minutes each hour, 18 hours a day, removing about 300mL each time. 10 minutes later pump 2 would run for 10 minutes pumping about 300mL of clean saltwater back into the tank. This would change about 5400mL (~1.5 gallons) a day. This actually amounts to ~81% every 30 days. I realize that this setup will result in some clean water being changed out as well, but that amount should be minimal in comparison to the dirty water.

The final component of the system would be the ATO system. The main dilema here is keeping the ATO from adding freshwater before the clean saltwater has been added to the system. In order to avoid this problem I would put the ATO on a timer that only allowed the pump to run during the 6 hours each day that the Water change system is inactive.

One added benefit to this setup is that this would leave one more pump that could be used for dosing supplements (I actually plan on buying an expansion unit giving me a total of 7 dosing pumps).

So what do you all think?

 

[ailachami]

i've seen this on a freshwater tank before. basically you can do a gravity feed or drip from your tank to a drain and have an ato pump water back into your tank. this was on a freshwater tank so no salt being mixed but you can probably get a system to monitor the salinity.

 

[djkms]

I did automatic water changes when I first setup my current build. I had to take it down because the lines snapped against the wall and ****ed off my wife. I used a litermeter 3 to do it. The biggest thing is making sure your pumps are calibrated and to check the calibration often so you are not slowly adding more saltwater then taking out or vice versa.

The ATO aspect is a moot point if your lines are calibrated properly. Even if it adds freshwater before clean saltwater it wont top off again until it evaporates to the point to top off. The change will be minimal with a continuous water change system, it balances out after the first dose of fresh saltwater gets put in the tank and the initial ATO evaporates.

Randy Holmes-Farley did the math and a 30% all in one water change is equal to a 27% continuous water change.

Just make sure to have the fresh saltwater added downstream of the water being taken out and you will get maximum efficiency.

I would still be doing a automatic water change system if the boss would allow it

 

[lpsouth1978@msn.com]

This will actually be on a planted freshwater setup. I will not have the tank near a drain for a gravity feed. I figure that, when calibrated properly, the dosing pumps should be more than accurate enough for this setup. Especially since it will be on a freshwater system, the only real concern would be that the tank does not overflow. I wrote this up as though it was going on a saltwater tank, because I may implement it on my reef if it works out on my planted setup.

djkms, good point on the ATO issue. I had not looked at it that way.