Water changes. Why??

[tanker]

Was wondering why am I doing water changes (at least why so often)?? I have lots of plants to "eat" nutirents. SF bay area water is so soft I have to add GH to get it higher. My nitrates and phosphates are low (because of all the plants), am even considering adding phosphate. I run carbon once or twice a month to "clear" water. I run a micon filter 24/7.
So why am I changeing water?? What am I removing??

[anonapersona]

Do you add fertilizers for the plants?

[RTR]

Because there are a lot of things generated in tanks that we do not and cannot test for without spectrophotometers, and even then we must ID them and set standards first. Organics which have long half-lives in aquatic systems, especially the cyclic compounds; hormones - which are functionally short-lived but their breakdown products may be lasting; simple nitrate - unless you are low bioload and high light - can be toxic at higher level, do you test? Water changes restore the buffering ability of the water (which is burned up with normal tank processes), reduce increased mineral content (which must be high in your tank with only top-off addition - do you check TDS versus tap water?), etc., etc., on and on. There are myriad materials generated in closed systems which are biological toxins and may or may not be removed by plants, especially in a low-light, no carbon supplement situation.

Water changes are simpler and cheaper and a heck of a lot faster than testing, even for all the things for which we can test and ignoring the larger numbers of things for which we cannot test.

I am not interested in maintaining inhabited cesspools, which IMHO is what unchanged tanks are sooner or later. YMMV.

[tanker]

Yes. 100gal. I add 15 drops of kent Iron (FE), 25 drops of K, a drop or 2 of Seachem Phosphorous daily. Add kent GH till hardness of 3, have CO2 injection (3+bubbles per second through am Eheim reactor). Doing 15-20% water change per week. Can I do 10% every other week, or even less??(10% per month??).

just wondering.

[djlen]

Agree with Robert. 'Clean' water is a tonic for the fish whether you fertilize or not. It becomes especially when you do fertilize however to prevent a buildup of harmful elements present in some fertilizers. ie. copper.
My fish just love the water replacements I do weekly. I only add new fish to my tanks after water change time as well. I feel that fish can accept/tolerate change with much less stress when the water is clean.
I think Tom Barr uses the term, "Reset your tank". That pretty much says it all for me.

Len

[tanker]

PS--I also have over 300watts of PC lights, but do have a very heavy fish load, but mostly tetras.

PSS--what is YMMV???

[Starry]

Originally posted by tanker
Yes. 100gal. I add 15 drops of kent Iron (FE), 25 drops of K, a drop or 2 of Seachem Phosphorous daily. Add kent GH till hardness of 3, have CO2 injection (3+bubbles per second through am Eheim reactor). Doing 15-20% water change per week. Can I do 10% every other week, or even less??(10% per month??).

just wondering.

The amount of P you're adding seems very low. I didn't do any calculations on what you're dosing, but I know I dose 6 to 8 mL per week in a 10 gal, this gives me about 1-1.25 ppm P at dosing time, and it's all gone in a week. Plants love it. You might want to increase this, and might want to switch to something else, because Seachem can be expensive in a big tank. People use Fleet Enema I think. Look into it. You want at the very least 0.5 ppm P.
K levels should be high rather than low as well. If this is seachem's potassium that you're adding, no way it is enough. Seachem K is super super dilute. Try KCl (salt substitute in grocery store) and dose to 25-30 ppm.
No time to write any more now, just trying to give you a heads up.

[LMOUTHBASS]

fish poop