OK i got the response from Bob Fenner this morning regarding replacing LR
and i thought i would share...
<Likely there are mentions of this issue stored on WetWebMedia.com but no
definitive explanation. I will try to be brief here: There is a general "trend"
in marine aquarium keeping with LR
and substrates seeming to "run out" of
soluble materials, capacity to sustain biomineral, alkaline (pH) over time...
that "crashing" syndrome is right around a year and a half after set-up... And
there is plenty of anecdotal evidence that the practice after this time of
removing or adding 10-25% or so of new LR
, substrate forestalls this effect...
So, my pitch on after the first year and a quarter, year and a half for
aquarists to switch out or add more of these materials... on a six month basis
thereafter. The new LR
of course does many other useful "things"... restoring
biodiversity, introducing new "fodder"... and aquarist interest! Bob Fenner>
He did say at the meeting that this can be done in your sump and/or other container.