[Max]

Not what they are but why we should do it?
Take your above average tank. Say like Steve Weast's for example. Or any other WELL equipt tank for that matter. You have live rock for filtration, A skimmer to pull the nasties out. Calcium reactor,sumps,DSB,macroalgae and the like or just the addition of all the right chemicals manually. Your water is perfect right down the line. What is the porpose of taking out good water and adding new water. Ive talked to some that say they never do water changes and some that do very few. Most people do changes ever week or so. Im confused as to what the actual cause and affect this has. Like I said above, in a WELL equipt tank. I can understand the need to replace bad water but if we strive to have the best setup we can like im sure Steve's is. At least from what I read, the man has EVERY known piece of equipment one could have but he still does massive water changes. Seems to me that everytime he dumps all that water it sets up an imbalance. A shock to the system unless your replacement water is at as close to all the same properties as the water you take out. And that is why I'm asking. If the added water is as close to the water removed, chemicly then why change it?

Sorry for the rambling

Max

[Samper]

Your salt mix has trace elements in it. When you do a water change you are replacing them since your system is using them up. I can't explain it scientifically but I read somewhere that the water goes "bad" after a while. Natural sea water is supposed to go bad quicker than synthetic sea water.

[Max]

That makes sence I guess but my natural response will be, Cant we add these trace eliments? We have everthing else at are disposal, why not these trace eliments? Water changes are a huge pain in the butt!

Max

[Poseidon]

It is a matter of removing things that MAYBE we cannot test for... Take for instance Zhenya's recent spawning event... His water parameters all still tested perfect! That is an EXTREME example, but demonstrates the point. There are other things that may be in our CLOSED environments that are not tested for that a water change will remove!

[Ninong]

Water changes add trace elements that may have been depleted but what is even more important, they remove undesirable compounds that might otherwise build up to toxic levels. It's a two-way street.

Whether you do water changes and, if so, how frequently and how large is a decision that is influenced by your particular setup. If you are running a large, complicated system with one or more very large refugia attached, you may not want to do water changes as often as someone with a different setup. The total bioload would be another factor that would weigh heavily in choosing a water change schedule.

Yes, Steve Weast performs regular water changes on his system. Wayne Shang, another respected hobbyist with more than 20 years experience, also performs regular water changes on his tanks. He does a 25% water change every four to six weeks on his 300-gal FOWLR tank and a 10% water change every four to six weeks on his 718-gal reef tank. What he actually does is use the old water that he is removing from the FOWLR tank to add to the reef tank to replace water that is being removed from the reef tank. The reason he does that is because his reef tank, in spite of its extremely heavy bioload, operates at less than 1 ppm nitrate and he needs the influx of nitrate from the FOWLR tank's water to keep his many large Tridacna spp. clams happy. Even after such a water change, his nitrate levels in the reef tank will be undetectable in less than a week. http://www.underseadiscovery.com/home.htm

[Max]

Well so far when I do a water change its 10% and I do it once a month. Just feels like im going through the motions but not really knowing if its needed. I have a small bioload Id guess at the moment unless the zillion small starfish and almost as many bristle worms add to the load to a great degree. Only 1 fish and a few small soft corals in a 55 gallon and pretty much the same in my 44.

Hard to argue that they arent needed when so many nice tanks get them regularly. Just wish I knew how much and when they are needed. Guess the older your tank gets the more you know what it needs and what it doesnt. So far im still a newbie. Going on gutt and questions asked here.

Thanks

[Reefland]

I would also say that it helps to improve water clarity. If you've never compared old water with new water side by side, you can't appreciate the difference and notice the potential impact that the aged water has on the light penetrating through the water column.

[saltjunkie]

it was explained to me once this way.. and it helped.
imagine you lived in a small 5x5 room.
and all there was , was the air in there,,, continually recycled and run through filters, but no new air was ever introduced. even though you could live in that.. the air would get stale and old.

may not be scientific, or even a correct example.. but it has always made sense to me..

[Max]

That makes sence, I guess I just put more faith in the ability of all the equipment to clean and filter the water than I should I guess. Dont get me wrong, My setup isnt anything as nice as Steve's but I would have thought that with all that equipment that the water would be better than any fresh water you could put in.

I do have a question that has confused me about some of that replies. Water changes are to put back trace eliments that are used up by our tanks but yet how can many trace eliments be left after RO/DI and such. I mean it sounds backwards. We want as pure a water as we can get but then we need it to not be pure. I know Im ranting and I do and will continue changing water. Just makes me go Hmmmm.

Max

[Reefland]

The trace elements that are mentioned are added to the RO/DI water when the salt is added; the artificial salts contains them.

[Max]

Thats right. Duhhh!!!. Got side tracked in my one track mind