Water changes

[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

[marie]

It's interesting that nobody is speaking up for the small water changes.

It was comments like this

Well I had done a 50 % water change a few days ago(risky I thought myself )

and this

Really what I would do is (here come the flames) a 80 or 90% water change

that got me curious.

It's not just canreef but on every reef forum I visit, there is a group of people who will tell you to never change out more then 10-20% of the water. I think that a lot of tank crashes could of been saved over the years if people were more willing to trust the lone person who says "Do a 90% water change"

[Aquattro]

Marie, I completely agree. While I regularly do 10 or 15% changes for maintenance, if I thought I had an issue that a 100% change would fix, I'd do it ( well, back when I had a 100g tub for mixing). The "rule" of 10% is just being safe and we always tout "make small changes slowly" in a reef, but properly prepared water is just like the water in the tank without all the crud in it.