Water changes?

[nixer]

They can but more due to the sudden temperature change than anything. Plus you have to consider the PH. Some decorations will buffer the PH over time. Like driftwood or coral. If you then do a huge water change, the PH will be different and that can throw them into shock as well. Tap water can be tricky. Mine is well water and is VERY hard. I cant get the water stats correct no matter what I do so I just use bottled water for every change now. If you have city water it will be more stable and better for water changes.

Another thing is some people think they should clean all the gravel and filters with every water change.. Thats a no no. If you do that, you remove all the good bacteria. In essence you will begin to "cycle" the water every time you do a water change. The cycle is the initial amount of time it takes for the nitrites to turn into nitrates from building a healthy amount of good bacteria. If there is any amount of nitrItes in the water, it will kill the fish or shock them so bad they may not recover.

So alternate water changes, gravel cleaning and filter cleaning, leaving at least a couple weeks in between each one. Gotta keep the good bacteria in there to keep the tank healthy.

It doesnt cost me much because I take three 5 gal jugs to the grocery store and fill them at their water filling station. Its only a few dollars per jug that way. The water where I go is reverse osmosis filtered and I check my water stats weekly. Have never had any fluctuations since I started using that water. Plus I have such an immence filtration set-up with 2 Eheim canisters (each with different filtration compounds inside), I simply dont need to change water very often. This also allows me to only clean one canister at a time to leave the bio load high in the other while the clean one recycles.

But many people who only have a 5 to 30 gal tank dont use canisters so they just cant get that type of filtration without having a huge OTS filter or 2 smaller ones. My personal rule of thumb is filtration rated for at least 2x my tank size. That way the natural bio load takes care of the rest.

what works is what works.

anymore you really cannot go by a filters rated tank size or the gph rating of it. there is way too many that are rated way higher than they should be. heck the xp4 is nothing more than an xp 3 with an extra basket! there is no increase in flow. unfortunately they are not the only ones to do this. if you look at ehiems site they have the ratings with media, but this is also brand new media, so you have to leave a big margin of error.

for those with smaller tanks its more important to have perhaps a undergrave filter and a hob filter. try to say away from those bag types they do not allow for anything when you change the bag! i stick with aquaclears.