a water-change based system?

[Anonymous]

I'm imagining a system in which the needs of skimming, calcium requirements, and even RO topoff are all met by regular and perhaps automated water changes. It seems like someone must have done this, but I don't recall ever seeing it...

 

[leftovers]

they are callled nano tanks...other wise the cost of such a system is prohibitive. Its relatively straight forward to do lots of small water changes every other day or so but the gains are marginal if only doing a small percentage daily or every other day. For such a system to be effective you need to perform 10% changes or better if I recall correctly.

That's where the cost factor hits, salt isn't cheap and 10% ever few days really begins to add up....

 

[Anonymous]

I'm imagining a system in which the needs of skimming, calcium requirements, and even RO topoff are all met by regular and perhaps automated water changes. It seems like someone must have done this, but I don't recall ever seeing it...

Old Skool nano tank methodology. 50%-100% water changes weekly. No dosing, no supplements, no skimming. Works well. No reason it couldn't work on a larger tank, aside from the Hassle Factor of doing it with a larger volume and expense.

 

[rbursek]

Here is some good reading on it, calcium would depend on tank needs,(amount of corals) and what salt you would use.
http://reefkeeping.com/issues/2005-10/rhf/index.php

 

[Anonymous]

Dan,

I do remember reading about someone automating water changes on a large system - there was like 5% changed daily IIRC. Don't have time right now to dig it up, maybe you can find it.

 

[Anonymous]

Dan,

I do remember reading about someone automating water changes on a large system - there was like 5% changed daily IIRC. Don't have time right now to dig it up, maybe you can find it.

There's a few threads on it in our club, thin king of that? They all use the Litermeter III for it IIRC.

 

[Anonymous]

Hmmm... so I guess if the tank isn't too big its doable. Water changes were always a hassle for me, but that's just because I never set it up and automated it to not be. I guess the cost of the salt is the main barrier to this. If you subtract the cost of skimmers and the electricity etc... it would probably still be more expensive. Damn sight simpler though.

 

[Anonymous]

I'm imagining a system in which the needs of skimming, calcium requirements, and even RO topoff are all met by regular and perhaps automated water changes. It seems like someone must have done this, but I don't recall ever seeing it...

Yes it's called an open system. All you have to do is have an unlimited supply of good water then run the system so that the water is constantly being added to the tank and the overflow is being removed. It can and has been done for those fortunate enough to live right next to the ocean.

But for more normal systems far away from the ocean we are forced to run what is basically a closed system where the tank itself processes the waste products.

Consider if you have "something" increasing at some amount each day. And you are doing water changes with good water at some fraction of tank space at constant intervals. The value of "something" just before the water changes reaches this:

Before water change=(increase between water changes)/(fraction of water change)+amount in replacement water.

For instance if you have a 1ppm/day increase in nitrates and are doing weekly 1/10 water changes with 0 nitrate water you have a 7ppm nitrate increase between water changes


before water change value=7ppm/(1/10)+0=70ppm. After the water change you have 63ppm then before the next water change you have 70ppm again.

So yes you can maintain parameters by water changes alone. As long as you are prepaired to do relatively massive frequent water changes.

So in order keep low nitrates in the above example you have to do very large daily water changes. For instance to keep nitrates at 1ppm you have to do a 100% water change each day.
my .02

 

[blackcloudmedia]

I think the only place that this would work is on the reef. I tried setting up a system like this a while back but the costs were just too much. I set the tank up so that the sump was where the water level changed, then I put a water topoff device in there. But I didnt have the money for the calc reactor and such. It would be cool if you could set up a float device on your RODI unit so you wouldnt even need a topoff device.

 

[Anonymous]

We all want to make things as easy as possible but IME most fail to consider that an ATO adds a failure mode. Should the overflow fail the ATO kicks in raising the display's (or upper container's) level which can result in a flood.

To prevent that you need a float switch to kill the return pump above a certain water level.

just my .02