Hello Victor and everyone I also build racks to keep my 10 gallon tanks end to end... One of my racks is three tiers high. One of the ways i solved problem between rows for water change purpose was to step the tiers... I have each tier 2-3 inches out from the tier above it.. this way i can still use buckets to fill tanks quickly.. top tier is closest to the wall, middle tier is out 3 inches and bottom tier is out 6 inches from top tier and out 3 inches from the middle row... I also only have about 8 inches between top of the tank and bottom of the row above it. I also use 2X4's for building materials on my racks. Hope this helps. John ------------------------------------------------------------------------- This is the apistogramma mailing list, apisto@listbox.com. For instructions on how to subscribe or unsubscribe or get help, email apisto-request@listbox.com. apisto-digest@listbox.com also available. Web archives at http://lists.thekrib.com/apisto Trading at http://blox.dropship.org/mailman/listinfo/apisto_trader