Posted: Tue Sep 19, 2017 10:51 pm Re: Water change frequency
I usually let evaporation do the water changes for me. The water evaporates at about a rate of 5-10 gallons every 2 weeks for me. I keep my 50 gallon stock tank 75% full. That's about a 25% water change that happens on its own for me. I do have a good water flow though, a larger than normal surface area (stock tank) and a bubbler (for the fish), so I imagine that all aids in speeding up the evaporation. The filter is packed with Seachem Matrix too; all it has is Seachem Matrix and some foam mechanical filtering pads. It's a filter rated for 100 gallons, and it keeps my 50 gallon stock tank running well. All of this keeps the water crystal clear, with very good water parameters. From what I've found, if your filter flow is good (have the output setup on one end of the tank and input on the other side), and you have enough turnover of the water (in the form of a 2-4 times the gallons per hour of your tank), with plenty of good filter media, you'll have good water.
Remember when cleaning out the filters and the tank to not get rid of all of that brown, nasty looking stuff you might find in the filter and in your tank - that stuff is gold. It's full of good bacteria, and only needs to be cleaned if it is restricting flow. Clean that stuff in tank water, and be gentle. You don't want to kill off too much of that bacteria, or else every time you replace that good bacteria with a fresh pad or filter media will mean starting the tank cycle all over again. If the filter media starts to deteriorate, and you want to replace it, you want to "condition" any new filter media you are going to use before completely removing the old media. Place the new media in with the old for several weeks, and let the new stuff grow bacteria from the old stuff.
Of course, the only way of knowing whether your water parameters are good is by doing a full chemical check of the water. Otherwise, a visual inspection is usually a good indicator if you are on the right track.