Why change my water?

[gdubs97]

This is a serious question. I have a 120 gallon tank with 30 gallon sump. I have always changed my water (30 gallon reef crystal mix). I run gfo, carbon and have been using probidio as well. I decided to start changing my water once a month. It's been about 4 weeks now and here are my parameters

Phosphate 0.04
Alkalinity 8.15
Calcium 425
Magnesium 1425
Ph 8.22

What benefit do I get from changing my water?

 

[Mpfaff77]

Adds back trace elements. I would also imagine it is refreshing to the fish as well.

Edit: nitrates reducer as well. What are you nitrates at?

 

[scolley]

Its a valid question. Presumably w/c's perform two functions... Replacing important things missing (like traces), and removing bad things otherwise not removed.

Regarding the former (removing the missing), I personally believe that can be accomplished without water changes. I add traces regularly. Just a little squirt every week or so.

But the latter - removing bad things not otherwise removed is the rub. Granted, carbon, GFO, and protein skimmers, and even (God forbid) turf scrubbers or macrophage, remove a LOT. But they are imperfect, and allow many nasty things to pass through their filtration, and build up to unacceptable levels. An example is heavy metals that make their way in through food. Sounds silly, yes. How much mercury gets in from my food? In a day... Probably unmeasurable. In a few years... Likely too much. But that's just one example.

Bottom line, w/c's value can be less about what you need to replace than what you need to take out.

But don't take my word for it. Go find one, well documented, SPS heavy tank that has had no water changes for five years. I've personally seen nothing to indicate such a beast exists. To even back off that and just find a really nice (good coloration and growth) SPS tank with no water changes for just two years would be QUITE a find, IMO.

 

[Sleepyhead]

WCs are also great for things we don't test for. Lysol, Febreze, anything else that is in the air.

 

[JoeBellz]

+1 wondering what your NA is at?

 

[spieszak]

scheduled water changes are proactive rather than reactive... you can likely go quite a while without them and not see problems in an established tank. The problem being that you really have no way to tell whether you are 1 or 2 or 10 days away from parameters going completely out of whack... and when they do, are you going to notice it 5 minutes before you leave for work?
"reactive" husbandry will eventually bite you unless you are absolutely keen on everything that is happening in your tank. Some can do it.. they can see mild changes in behavior even when water params are spot on (according to the test kits that have a reasonable margin of error, and can't test in the minutia that we would really need to be able to reactive husbandry work)..
So, I in general wouldn't say that if you aren't doing them weekly, or monthly you are going to have problems. Stretch them out if you are comfortable that your tank can take it (remember every time you add something, what your tank "can take" changes).. but rather to shoot for a blend of proactive rather the reactive, rather than either/or....

 

[gdubs97]

I hear you guys. How often do you guys change water? Every other week is just a pain for me and I am going to try every 4 weeks from now on and of course monitor things.

What is NA?

 

[KRAZE]

Its a valid question. Presumably w/c's perform two functions... Replacing important things missing (like traces), and removing bad things otherwise not removed.

Regarding the former (removing the missing), I personally believe that can be accomplished without water changes. I add traces regularly. Just a little squirt every week or so.

But the latter - removing bad things not otherwise removed is the rub. Granted, carbon, GFO, and protein skimmers, and even (God forbid) turf scrubbers or macrophage, remove a LOT. But they are imperfect, and allow many nasty things to pass through their filtration, and build up to unacceptable levels. An example is heavy metals that make their way in through food. Sounds silly, yes. How much mercury gets in from my food? In a day... Probably unmeasurable. In a few years... Likely too much. But that's just one example.

Bottom line, w/c's value can be less about what you need to replace than what you need to take out.

But don't take my word for it. Go find one, well documented, SPS heavy tank that has had no water changes for five years. I've personally seen nothing to indicate such a beast exists. To even back off that and just find a really nice (good coloration and growth) SPS tank with no water changes for just two years would be QUITE a find, IMO.

http://reefkeeping.com/joomla/index.php/current-issue/article/119-tank-of-the-month

He claims its been 3 years and 8 months at the time of the article, so i guess it is possible. I personally know of several mixed reef tanks that contain sps and get water changes just a couple times per year, and they are doing very well.

 

[scolley]

http://reefkeeping.com/joomla/index.php/current-issue/article/119-tank-of-the-month

He claims its been 3 years and 8 months at the time of the article, so i guess it is possible. I personally know of several mixed reef tanks that contain sps and get water changes just a couple times per year, and they are doing very well.

That TOTM IS a find! Thanks. So it DOES happen. But is still rare. And FWIW, three and two thirds years is mature tank - nearly the five I indicated. So I wonder what I'm missing? Why can he do that, but so few others can?

And as to tanks that get water changes a couple of times a year, that's not at all the same thing as NO changes. That's INFREQUENT changes, which is a very different conversation. Thanks for posting that though. Sheds some light on the question. :thumbstup:

 

[gdubs97]

Wow
See his parameters
Magnesium, phosphate and nitrate - never tested!!

 

[thefuz]

Yeah, Nano's got a combo of DSB and bacteria dosing, amongst other things. The thing I see as common in long duration w/out water change tanks is the DSB. I've been thinking that if the problem with DSB is crash after a certain period of time (3 years is it, on avg?) then why not set a pair of them up staggered by 18 months or so... then just replace one when it gets to be "old". Not scientific at all, but theorized based upon the empirical data at hand.

 

[scolley]

..then why not set a pair of them up staggered by 18 months or so... then just replace one when it gets to be "old".

Back when I thought I needed a DSB (changed my mind on that), I planned on doing exactly that for my next tank. I use carbon in bags now, 1/2 cup in two bags, changing one bag every two weeks. Carbon's not a DSB, but the point is the same - no replacing everything at once. Except that removing 1/2 of your DSB might have a big effect, so I was thinking about creating four removable sections in my sump as the DSB, and just have all four on a rolling refresh cycle changing one every six months or so.

Another things I noticed in that long-term, no-w/c tank, is very, very little livestock that is not coral. I can only see one cardinal and a couple of clowns. So he's feeding real light. That can't be a coincidence.

I'd love to know his feeding regimen (coral and fish). I'd also be real curious to see how long this keeps up.

 

[jrmx635]

I have a 120 and haven't changed the water in 6 months.
my tank looks great.
I've been in this hobby for like 13 years and used to change water all the time.
you can tell what your tank is doing just by looking at it after this many years.
however w/c's are important and I am do.probably I'll change about 40 gallons slowly and vaccuum out the sand.
these days with GFO,biopellets and refugiums,the tanks can do much better than 10 years ago.