Live Rock vs. water changes

[singold]

Will more LR equate to lesser necessity for water change interval times when comes to Nitrate levels?

eg. 75 gallon tank --- 60 lbs. LR --- 10% water changes every week and a half

compared to:

75 gallon tank --- 100lbs. LR --- 10% water change every 3 weeks

* I'm just trying to get a correlation on this, I have read and heard more LR keeps bioload down, thus Nitrates I would assume, thus less often water changes.

Any advise or recommendations on this? Thanks in advance

 

[metweezer]

LR is your main biological filtration. You should have between 1 & 1/2 & 2 lbs. per gal. However you still have have to do water changes. Trace elements can become depleated and the salt in your new water changes replenishes these trace elements.

 

[FishDoc]

Unfortunately I don't think the relationship with respect to nitrates is that simple. Even if you assume bioload and feeding are unchanged, that last step in break down of nitrogenous waste, from nitrate to nitrogen gas which will then leave the tank, takes place in low O2, but not anaeorbic conditions. Thus the amount of correct "micro-climate" condusive to break down of nitrate to nitrogen gas depends on a multitude of factors, flow being one large one. I would say the only way to tell for sure would be to do the experiment, run the tank with X amount of live rock and set water changes and measure nitrates periodically, esp right before and after a water change. Then add additional live rock but continue with the same schedule of water changes, and measure nitrates at the same times relative to water changes and see if they are different. If they are signigicantly less, you might be able to stretch out the interval between water changes. But, as metweezer points out, that still doesn't do anything about the trace elements, and phospates which also must be monitored and controled either through water changes or a phospate remover.