DIY Auto Water Change System Design

[rotaryblake]

An RO filter wouldn't work. An RO system would have a high rate of waste water, and the product water would be void of essential minerals. Then even if it did work, you'd constantly need to replace the filters and perhaps the membrane, which isn't cheap. If the idea is to save some money and waste less water, just add some fast growing plants to your set-up. Maybe read the sticky: "Cheap plants, less nitrate! POTHOS" in the DIY Filters sub-forum.

Some very good advice right here. Reducing water changes with minimal cost and maintenance is always a good idea.

It would be pretty cool to integrate old aquarium water into a grey water system though, to do things like flushing the toilet or running the sprinkler.

 

[Ryan_R]

I did the math a while back, and even with big weekly water changes with 300 gallons worth of tanks, it was still a small percent of my monthly water bill.

-Ryan

 

[predatorkeeper87]

2 things:

1. Nitrates are only going to disappear if that 3rd tank is filled to the brim and back with pothos and duckweed plus having more in the main tank.

2. in writing that first thing I completely forget my second point, but I hope it works, there are some solid theories in here for filtration, good luck!

 

[paulW]

I put a sulfur denitrator on my 300g. It dramatically reduces the amount of water changes I need to do.
My tank is heavily stocked with Malawi fish.
Lots of info on them in the reef forums, but they work on fresh water tanks too. You can even find DIY plans, but watch ebay and you can get used
ones cheaply.

It basically converts all nitrogen waste products to nitrogen gas. You still need to periodically vaccum the tank bottom and do water changes, but the big reason
(at least in a crowded tank) to do water changes is to manage nitrates. Of course there are other benefits to WC, but at least in my situation, I do a lot fewer changes.
I didn't do it to save money, I did it to reduce labor.

Another great side effect is, zero nitrates means almost no algae growing. Water gets crystal clear.

 

[D.Wolf]

As far as im reading, sulphur denitrators can cause problems when used in soft water because in denitrification process, acid is one of the products.. when using with mbunas, there shouldnt be a prob

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[dlp40]

An algae scrubber would work wonders in your quest to reclaim water. I have used one on salt water reefs before with great results. I also used one one an out door pond with equally good results. I would think in your situation one should be a fantastic way to get rid of Nitrates.

 

[paulW]

As far as im reading, sulphur denitrators can cause problems when used in soft water because in denitrification process, acid is one of the products.. when using with mbunas, there shouldnt be a prob

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True, I haven't tried it in soft water systems.
I am not sure how much acid it actually makes though.
The system gets the nitrates down to zero pretty quick, after that, there's relatively little action.

The instructions said that if you are using it on a soft water/low hardness system, that you shouldn't put in crushed coral to consume the acid.
Seems like they are more worried about raising the alkalinity than an acid pH crash.

But yea, you're right though, it's something to think about.