Water changes

[Lampshade]

http://reefkeeping.com/issues/2005-10/rhf/index.php

This is a great article that proves sphelps point for doing water changes.
I agree to doing them if you need nitrate reduction, add in "extra" elements to your tank through dosing, or need to replenish mag/calc/alk.

I run biopellets/large refugium that keeps my nitrates at 0, I don't dose(Calcium Reactor), so the only "extras" I'm adding to my tank are through the food I feed my fish, or trace elements that make it past my RODI(should be 0). So in an ideal world, there's no reason for me to do them weekly/bi weekly. I've been doing them recently since my tank's been recovering from the epidemic "Kent Carbon '12", just because of the excess die off that's been happening my ecosystem cannot keep up, so I've had to intervene. But generally, I've had best results letting everything stay balanced, whatever my coral takes up in elements, my calcium reactor adds. Whatever waste is produced, my bacteria/refugium/skimmer take up. Every time I did a 10% water change, my coral would lose color for a week. Now that my tank's back to going better I'll be changing from 10% weekly back down to 10% monthly over the next while, so that I can try to get the color back into my coral's since they're back to growing again.

[sphelps]

I already posted that article but apparently most peoples attention spans are not long enough to read such a novel. It's easier to blatantly ignore everything and post the same dribble over and over again.

[sphelps]

I'm also not sure where people got the idea that 10% weekly is the norm or what's apparently recommended as a rule of thumb. I don't believe this to be true, as far as I know 10% monthly is what's recommended as a rule of thumb to simplify things for beginners. From there each hobbyist determines what works best for them, whether it be more or less depends on their tank demands and experience. Systems like Zeovit call for a 10% change weekly but there are specific reasons for this.

This is not a new concept, it's how it's always been so if people are debating whether to change X amount weekly or Y amount monthly or even Z amount quarterly you're really all doing the same thing. Changing water, the amount and frequency is only thing different.

Eliminating water changes all together is different story but it's also nothing new and been going on for decades. It's not new technology that people haven't adapted yet, it's simply a different method that few people use long term for what I believe is the simple concept of excess organic and inorganic impurities that will build up over time as well as imbalance of elements.

[sphelps]

On more post regarding cost of dosing vs water change as that came up.

System size: 25 gallon
Demand: Low

Water change:
Decent salt brand - $70 / 150 gallons
Min requirement - 10% change per month
Cost: $ 1.17 per month

Dosing (rates are based on bottle instructions):
Trace Element - $20/500ml (5ml/week)
Mag - $10/500ml (5ml/week)
Potassium - $12/500ml (2.5ml/week)
Alk - $8/500ml (10ml/week)
Ca - $10/500ml (10ml/week)
Cost: $2.88 per month

So dosing will cost you more than twice as much and do less but it is easier.

[Arok3000]

That article also conclusively explains what Sphelps is discussing about removing unwanted build-up of contaminants.

Water Changes to Deplete Something: Sulfate from a Homemade Two-Part Additive

I have suggested that reef aquarists who cannot find high quality magnesium chloride could manage using inexpensive Epsom salts (magnesium sulfate heptahydrate). The unfortunate drawback of using Epsom salts is the accumulation of sulfate. The article goes on to show how water changes reduce the concentration of sulfate that is built up as a byproduct of splitting the magnesium sulfate heptahydrate.
Now I know that many aquarists are not using Epsom salts to dose their magnesium, but what other by-products are you unknowingly creating in your tank?

I use FCC grade anhydrous Calcium Chloride which is claimed to be 99.8% pure. Can you be completely sure that the other .2% of whatever you're dosing isn't building up contaminants? Food grade products are fine for human consumption, but in our digestive systems we don't typically build up toxic elements, they are excreted through wastes. In aquaria, these elements are built up in the water column, and without a means of removal, will continue to build up over a period of time. Although not immediately noticeable, even the tiniest amount of pollutants consistently added over a long enough period will eventually build up to toxic levels.

[reefwars]

I have to agree with sphelps 100% very we'll said