Doing super frequent water changes.. what can go wrong?

[kien]

I want to try an experiment and was wondering about a couple of things. What i want to do is try to achieve an ULNS by doing very frequent water changes. Like, i'm talking 10% every 2 to 3 days. I have a 150g system so that's 15g every 2 to 3 days. What I'm wondering is what will be the fallout? I suspect the natural fauna of the tank could be diminished, but enough to be a problem? Has anyone ever tried this? Searching through the forums it seems the average minimum is about a week for a water change. My logic is that the natural ocean works well because it is highly diluted. Well, I figure if I inject new saltwater very frequently then I could nearly achieve this. So what's wrong with this logic?

[bauder1986]

hmm, interesting thought. Well I cant see anything bad about it, concidering when you have a najor nitrate issue, you ussally want to do frequent water changes. And all your doing when doing water changes is taking out old water and adding fresh new water with replenished elements in it. Now i suppose the reason why most people stick to weekly water changes is because its cheaper, yet still making sure that the tank stays healthy at the same time.

I would say try it out, and tell us of the outcome.

[mark]

Ulns?

[freezetyle]

Ultra Low Nutrient System

[simplycoral]

I maintained a similar routine with a tank a few years back...

Every 3rd day i changed out 10% for over 6 months. I never did notice much of a difference. The nutrient levels did seem to reduce initialy, but i found that the skimmer would hardly produce any skimate. I suspect this was down to the dilution of waste although the skimmers weren't the best back then. Believe it or not, I did notice the nutrient levels actually increase over the long run! I put that down to the fact that i was using tap water and not R/O.... I think i was putting much more of the bad stuff back in

Ended up being a Chore.

Would be interested to know how you get on.....

Simon..

[Delphinus]

The biggest fallout is the cost of salt.

It's actually not that new of an idea. I'll have to check back some old threads but there are several articles are written about the idea of water changes and how basically there is a point of diminishing returns with them, and basically, not unlike feeding, "smaller more often" is better than "larger less often". Some systems in fact incorporate constant water changes - ie, there is always a steady stream or drip coming in and it just overflows into the drain. Some captive breeding systems are setup this way. You would have to measure your salinity though regularly and manually compensate for the drift.

To be honest though I'm not real sure you'd get a "true" ULNS out of increased water changes. Your rate of export has to match or exceed your rate of production and since one is steady state and one is stepped, I don't think you will truly get there. I think the tank will certainly benefit, but it's not an as aggressive method of nutrient removal as the bacterial based ULNS's.

I think it really comes down to time, energy and cost. Otherwise it's pretty much just win.

[jimbo222]

hmm maybe no need for a skimmer anymore mith that many water changes

[kien]

I did think about the cost and reasoned that the amount of salt that I would need would probably be near what larger systems, say, 280g and up would use on a regular basis anyway? Plus, if this did produce an ULNS then that would eliminate the need for additives, but it sounds like this wouldn't be the case

.. thinking out loud here.. I wonder what would happen if you did frequent enough water changes to the point where the water in the tank was (nearly) constantly equal to fresh saltwater. Like say 90% fresh saltwater all the time?

[bauder1986]

well your corals would grow nice and fast and the fish would be healthy thats for sure.

[Red Coral Aquariums]

Originally Posted by kien

.. thinking out loud here.. I wonder what would happen if you did frequent enough water changes to the point where the water in the tank was (nearly) constantly equal to fresh saltwater. Like say 90% fresh saltwater all the time?

I would be nervous about losing your beneficial bacteria causing a mini cycle. I've seen a tank crash from 3 times 60% water changes and each one was done daily. 4 th day before h2o change ammonia reading was 3. This person wanted to bring down his nitrates from 20 to 5. He saved his tank by doing 10% daily water changes for a week. Subsequently after that week his nitrates were 7.

Kevin