slow/no monti growth

[ryanrid]

All my acro are growing like crazy (1cm a month) but my monti get little to no growth at all. Colour is great but encrusting takes months.

tank is full zeovit system with following params

p04 - 0.00 (hana meter and checker)
n03 - 0 (salifert low range)
cal - 400-420 (salifert and elos)
ph - 8.2-8.4
alk - 7.01
mag - 1350

lighitng is 10x54W ATI PM, water movement is 3 x MP40W tank is 120gal

any ideas why no growth on them, have checked for pest and are none, all corals are dipped in revive and quarantined 4-6 weeks before entering system also.
I find it strange i have acro encrusting within days whilst monti's take months.

 

[jimsplace]

A few mental notes I've noticed over the years about my monti's; they don't like being dipped (tend to sulk for awhile afterwards), you also might try bumping your mag just a tad, maybe a little higher alk? What varities are you trying, some are really slow growers.