Hmmm, but I might sit in the same bath water if it was constantly circulating through a waste treatment center, filtered and then heated and put back into my tub. :)

This is a very good question and I'm curious myself. We are all trained to believe that a water change is the bees knees, but if you're running on balling, have a really good skimmer and run carbon to take out dissolved organics, then is it ?

I do agree that the NSW helps to, well, freshen up the water, but is it needed ? Who knows. :noidea:

It would be an interesting experiment. Although possibly a difficult one to conduct.

Not sure how many of you guys monitor orp, I can tell tho from that level when to do a water change it hovers around 340 about a day after a water change, naw is around 250 but once it recovers I watch it and when it starts to fall again I do a waterchange. I can notice if I leave it drop a little more things start going a little funny.

I think that's a reasonable question only if we assume a close to 100% efficiency in our methods of removing and adding things. But I'm sure for every cup of crap my skimmer pulls, it leaves a cup. Carbon? Is it removing everything bad? For how long? What is dosing/balling adding that we don't account for? Is it harmful if it builds too high? In my mind, all these things simple prolong how long you can go between changes. For my comfort level, that's 2 weeks. Maybe I can go longer, maybe not. There's really no way to tell. So based on the effort it takes and the cost of salt and water, I've chosen a schedule that works for me, my wallet and my tank. As I said earlier, using the same equipment across multiple tanks, this one, with the more frequent changes, is by far my most successful tank. YMMV :)

I don't, but may start based on your observations. Would be interesting to watch. How are you doing this?

This is something that I've consider monitoring. But thought irrelevant. Ypu could control your orp to remedy this problem though I would wonder the cost vs wc

I would then argue that controlling ORP with external influences is simply masking an underlying issue (to a degree). Again, it may extend the window, but not make it irrelevant.

I monitor ORP because I run ozone and I do notice that after a water change my ORP reading hits the floor. I keep my tank around 325-350 between water changes but after a change it goes down into the 1xx range. It will take the better part of a week to get it back up. What does that mean in terms of the need or benefit of a WC? I dunno, but I'm not stopping my bi-weekly change to find out. I will let the braver people experiment with their tanks :)

Water clarity does seem better when my tank ORP is in the 350 range as does the vitality of the fish. Similarly my inverts etc. all seem to love the higher ORP readings.

I do have an ORP probe and it does fluctuate up and down. I never really payed much attention to it because it didn't move all that much. Even when I'D go a month without a water change I never noticed a significant change.

We all know that every tank is different so ya, your mileage will definitley vary. What's interesting is that there are people who do very little water change and seem to get by just fine. The water change schedule is all over the map.

I'm kinda in the same boat as you. I'm on a two week schedule that seems to work best for me (and my wallet too). I used to do weekly but can't accommodate that anymore. The tank doesn't seem to care.

My system is about 100g vol.
No probes, carbon, or pellets no gfo
Lots of blue clove coral though LOL (must be a great filter)
I do 5 gal change twice weekly. That's what works for this system and for me.