when does a water change become irrelevant

[kien]

Originally Posted by Aquattro

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 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.

[don.ald]

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.

[FishyFishy!]

Does anyone recall the DSR (Dutch synthetic reefing) method? There is a lot of controversy surrounding it, but it does make a lot of sense when you look at it. Simply replacing all elements that diminish over time, and zero water changes. Glenns 300 gallon tank on reef central is outstanding, and he hasn't done a water change for maintenance in years (not to mention he dosn't have a functioning skimmer, and very little equipment other than dosers). A very neat theory, but theres no way that I could keep up with all the testing all the time. I think regular water changes are going to be the key for me.

When I look back at it, all of my successful tanks were those that had regular water changes. All the ones that I neglected to do water changes on, had zero abilities to grow and keep even the simplest of corals.

[sphelps]

The Zeovit method requires water changes, I believe the guide states 10% per week to maintain the element balance. As far as bailing goes the idea is to increase stability between water changes, pretty sure it's been stated many times it doesn't replace or reduce the need for them. The way I see it is you're adding elements to replenish those being used thus promoting stability but at the same time there's pretty much zero chance it's being all replaced at same ratio it's being used. Water changes will maintain the balance by removing and replacing, cutting back on them would reduce overall stability thus defeating the purpose of the bailing in the first place. So as far I'm concerned the addition methods you've employed are additions to reduce nutrients and promote stability but have no relation to making water changes irrelevant.

[Aquattro]

Originally Posted by sphelps

So as far I'm concerned the addition methods you've employed are additions to reduce nutrients and promote stability but have no relation to making water changes irrelevant.

I would agree that this pretty much covers it.

[Simons]

My thoughts are no matter how good, efficient or over sized your skimmer is, it will never be 100% affective in removing all organics.

Most people that I know who run tanks and do small or no water changes also usually have a very low bio load, AND they feed sparingly.

If you think from a closed ecosystem perspective, when living organisms are present they introduce waste. Yes carbon, GFO etc help in that removal but they are never perfect.

I think toxins, nitrates etc build up over time in all tanks, just some build up much slower than others (bio load, feeding habits play a huge role in that department) but eventually levels will build up.

The advantage to very slow build up is anything alive has more ability to adapt over the longer period. So I don't see it as 'never needing' but perhaps needing less frequently but still needing (to do water changes).