Once per month but it really should be every 2wks. 180g w/100g sump, total volume of about 200g. ATB medium cone skimmer, mb7 and vodka, still use gfo
(because I don't shoot for undetectable nitrates). Dosing 2 part with a bubble magus doser. Feed the fish like crazy and usually test between .2ppm and 5ppm nitrates (using lamotte), depending on how diligent I am with the vodka. I don't even bother testing phosphates as I don't want to buy a meter and ALL of the "kits" are garbage. I also don't test ph because it's a transient reading that will lead you unto ruin if you try to micro-manage it with dosing.
I agree that water changes are a very inefficient method of removing nutrients. Not to mention that water changes suck, and as such, you wont need a very good excuse to put the job off for another day. So, if water changes are the main means by which you export nutrients, you will likely end up with a high nutrient tank. ]
In my, and only my opinion, there are a few items that are "cost of doing business" items. 1. a good effective skimmer (doesn't have to cost a million dollars), it just needs to be effective. 2. ATO, you simply don't have time to manually dump ro water into the tank, when the tank should have ro added, No ATO, means less stability, period. Don't even bother arguing this one with me. 3. If your into sps
either dosing pumps or a calc reactor, for the same reasons as the ATO, if it's a PITA you'll blow it off sooner or later. Lack of stability leads to a drastic rise in tank issues, particularly with sps
I find it amusing how many people try to save money on hard goods and then buy $100 frags and lament when they just don't perform.