When do you do your WC/ maintenance and what's your levels.

[The Guy]

Curious on what other reefing folks do and their maintenance routine.This is my routine I do water changes about once a monthish and my readings are pretty steady as follows and checked weeklyish:
mg 1400 manual dosing when required.
salinity 1025
alk 8.3 dose very little daily with a single doser as advised by Jeff at J&L
ca 420-50 mostly softies and LPS and few SPS manual dosing when required.

[Aquattro]

I have been doing 50% twice per month. Might cut that in half this year.

Ca 430
alk ~9ish
Mg - never cared

PO4 - aim for 0ppm, 0.02ppm is acceptable.
NO3, aim for 0, apparently nothing in my tank cares if it is closer to 50ppm

[Ryanerickson]

I do a water change when my phosphate goes above .07

[whatcaneyedo]

I perform a 15 gal water change each week but thats only 5% of my total volume. Each month I'll change out 1 cup of carbon and GFO which is again pretty minimal for the system size. Ca and Mg I'll test once a month as they don't fluctuate by much and after a few years of 0 I stopped testing PO4 and NO3. Alkalinity on the other hand can really jump or crash on me so I have to keep a close eye on it. I use a Ca reactor and Kalk reactor and once or twice a week add a few drops of Lugol's Solution.
Ca 400 - 500
Alk 9.5 ATM
Mg 1400
1.025
78 F

[Reefer Rob]

Winter schedule:
Approximately 10% water change weekly
Carbon changed monthly
GFO changed every two months or earlier if I see any algae in the tank.
Last readings:
Ca 420
kH 8.0
Mg 1290
PO4 0
NO3 0 but can be raised to detectable by dosing amino acid. Still not sure if there's any advantage to slightly detectable NO3.
Just started dosing Zeovit PIF.
Plan on trying some iron in the near future.

Summer schedule:
Whatever I get around to.

[Myka]

I usually do once a week water changes, but sometimes I skip a week. The tank is still young, and I find young tanks do better with more frequent water changes. I change carbon once a month or whenever the used saltwater looks yellowish in my 5-gallon pail (whichever comes first), and I don't use GFO or any other nutrient reducing agents.

Cal 400-410 ppm (kalkwasser on doser)
Alk 7.2-7.5 dKH (kalkwasser on doser)
Mg 1300 ppm (add 1 tsp to WC water)
K 400-420 ppm (don't dose at all yet)
NO3 0.00-0.25 ppm
PO4 0.00-0.006 ppm

[SeaHorse_Fanatic]

Just did one New Years' Eve. Before that, my last one was in the summer. I would do one every month or month and a half if I could find the time/ambition, but it seems like every few months is the best I can manage over the long-run. Luckily I have big sumps (90g wide) with two skimmers (Deltec AP702 and Deltec SC2060 skimmers (rated for 375 gallons), multiple reactors with Hydroton, lots of different macroalgae in the refugium, etc. to help keep up the water quality between water changes. On the 165g, I do massive (if infrequent) water changes of between 80g and 100g. On my RBTA/Dendro/Pulsing Xenia 93g cube, I usually do 40-45g water changes.

I don't necessarily recommend MY water change schedule for others but that's what I have been doing due to my unusual work schedule and the fact I need to place two 55g water barrels in my living room when its time to do a water change.

Anthony