Water changes

[marie]

Originally Posted by justinl

during emergencies, large cahnges dont always make the most sense. I agree that sometimes it's a good idea, but certainly not always. especially if you're not really even sure what the problem is. a 30% change during those times, i think is enough most of the time just to give you time to figure out what your problem is.

I think I disagree with that, unless you pick up a bad bucket of salt (which can happen) I can't think of any problems that can't be solved with a large water change. (I'm not talking about hitchhiker crabs, aiptasia, fireworms or the like kind of problems)

Edit, Ok I lied I just thought of one instance and that is starving corals

[Quagmire]

I do 50% weekly water changes and have never had a problem.I try to match salinity,temp and buffer my alk couple dkh higher, ph is usually close .But they are never an exact match.The only problem I can think of when doing a large emergency w/c,as long as parameters are in order might be light shock due to better light penetration in clean water.Think of the ocean,an area the size of our tanks get a 100% w\c numerous times a day.

[justinl]

well unless you have already identified the problem, i think the problem with the large changes, given that the new water is good and temperature matched as well, is that something will be changed drastically... and not necessarily something you can/do test for. there's so many things that might be off taht we just cant account for... we dont even know the complete chemical composition of real seawater. while a large change can be good, it's not something to be done blindly or regularly imo. if you do know what the problem is, then yes, act accordingly.

yes i agree that a large change can solve quite a few problems, but most times, the aquarist doesnt know what the problem is (which is my point), and there are inherrent risks in a large change itself. i suppose it's a balance thing. does the risk outweight the benefit, or vice versa? i dont think we can generalize that.

Q, yes, a single area of a few gallons in the ocean does get a 100% change many times a day, but that is not a rational comparison due to scale. it's like taking a look at one cubic centimeter of our tank and saying, that it gets 100% water change numerous times a day within our tank. but a change with what? the same water that was previously occupying it. so really, nothing changes. i suppose you could say the ocean is a small tank with a near infinitely large sump... which obviously cant compare to a closed system tank.

[marie]

yes i agree that a large change can solve quite a few problems, but most times, the aquarist doesnt know what the problem is (which is my point), and there are inherrent risks in a large change itself. i suppose it's a balance thing. does the risk outweight the benefit, or vice versa? i dont think we can generalize that.

But what are the inherent risks exactly and are corals stressed by a large water change (other then being out of the water for awhile which happens in the ocean at low tide all the time anyway).
If you are using the same salt that you always use and the salinity and temp are matched you should be good to go.

This is what I'm curious about, has anyone done a large water change, stressed their corals to the point of dying and can definitely say it was the water change that did it?

[Quagmire]

Originally Posted by justinl

Q, yes, a single area of a few gallons in the ocean does get a 100% change many times a day, but that is not a rational comparison due to scale. it's like taking a look at one cubic centimeter of our tank and saying, that it gets 100% water change numerous times a day within our tank. but a change with what? the same water that was previously occupying it. so really, nothing changes. i suppose you could say the ocean is a small tank with a near infinitely large sump... which obviously cant compare to a closed system tank.

I don't think the comparison is off at all,assuming you have parameters in check.Say in the ocean a clam dies,the current replaces the foul water around the clam which dilutes and dissipates.Althogh the replacement water come from the same body of water,it is fresh and clean,where as the old water was foul.If you are using the same salt,mixed to the salinity,at the same temp and PH,for a water change,then it is no different than what is in your tank,only fresh.
I'm not saying the w\c will fix the problem,if the above dead clam was in a tank you would have to get it out or the tank would foul again.
But the w\c in itself won't cause a problem,aside from the possible light shock mentioned in my first post.

[SeaHorse_Fanatic]

I have done 50% water changes many times before & when I upgrade my tanks, I usually use 40-50% of the original water & add new water for the rest. I find my corals loved these massive water changes (as long as salinity & temp. were close). Two weeks ago, I did roughly 120g worth of water changes on my main system & everything is thriving.

Anthony

[tang daddy]

I never have to drain the main display for waterchanges only the sump, therefore the corals remain in water but I find large water changes good for certain corals ie softies but not too well for sps anyone agree?

[marie]

Originally Posted by tang daddy

I never have to drain the main display for waterchanges only the sump, therefore the corals remain in water but I find large water changes good for certain corals ie softies but not too well for sps anyone agree?

I've never had a problem in the past with large water changes and sps. Of course the last 18 months all my sps are in my 175g and I don't have a mixing bucket big enough to do a large water change, I wish I did

[Delphinus]

I did a 100% water change once, solved my nitrate buildup pretty lickedy-split But it was a 20g tank and it had no fish, only a carpet anemone and some corals. But they all liked the outcome ...

There are times when I look at my 110g cube tank now with its elevated nitrates and I wish I could do a 100% changeout, I just don't have enough reservoirs to do it (and I have fish in there so that's no good). But I'd love to be able to change out even 50% or 75% of it just to be a kick-in-the-melon to the nitrates that are there.

Other than the bad salt (Kent, about a year ago? Maybe 2 years ago now, when they had that alk issue??), I've never had an issue from the waterchange itself. But yeah, I do match the temp and SG carefully, and do the premix for 24 hours thing too, so that probably helps a bit. I'd hate to see the results of a large scale water change that introduced a drastic temperature change.

I tell you one thing though, and maybe it's worse for me than others since I have tanks that have at least 5 years of crud buildup in the plumbing, when I turn the pumps off and turn them back on, the stuff that comes flying out of the sump return outputs is something I wonder if it would be better off not having been disturbed and released "en masse" into the water (ie, did I just invalidate my water change). I need a way to scrape out the pipes Or maybe it's better just to redo the plumbing every few years or so

[ron101]

Originally Posted by marie

I think I disagree with that, unless you pick up a bad bucket of salt (which can happen) I can't think of any problems that can't be solved with a large water change. (I'm not talking about hitchhiker crabs, aiptasia, fireworms or the like kind of problems)

Edit, Ok I lied I just thought of one instance and that is starving corals

I agree. If the water has some sort of contamination a small water change is unlikely to lower the concentrations enough to fix the problem. Of course you dont want big temperature or salinity swings but those are easy enough to match up.

Many reefs are close to the surface and experience salinity changes with rain. It doesn't wipe them out.