Why am I changing water?

[colinsk]

Thank you, Tom, for your thoughtful response. So you use the Estimative Index (EI) method. This makes sense if you are trying to create a beautiful centerpiece with little effort. I think you are right, this is what most people want from an aquarium.

I got into this to explore an ecosystem. It is a long term science experiment for me. It is also a tool to teach my daughter ecology. There are lots of very interesting lessons; from stoichiometry to physical chemistry to organic chemistry to microbiology to biology to ecology. I think the rewards of understanding this system are great.

My theory is that if you add ferts it is easy to get out of whack. The ratio of elements in any living organism is pretty close to each other. Whether you are feeding animal or plants as food the ratio of elements is pretty close. This is also the ratio of elements that your plants need unless the aquarium locks up the nutrients like binding iron or binding calcium and phosphates. So if you want to add a nutrient you must be very careful and understand why you need to add that particular element. This is getting to the heart of my query.

 

[colinsk]

Update: I almost made it 5 weeks and finally tonight I changed 33% of the water. All of the nitrogens read 0. The plants have been growing great and the fish are doing fine. The shrimp have been molting and the platies have produced fry.

In researching what happens with no water changes one of the most compelling arguments is allelopathic chemicals.

http://en.wikipedia.org/wiki/Allelopathy

The people who don't change their water and rely on plants to do all of the filtering also can only grow 3 or so species because the water gets filled with allelopathic chemicals. This seems to be a double edged sword. On one hand they inhibit algae and on the other they inhibit other plant species.

The final reason was I was just going to feel better if I changed some water.


Here is a picture before the water change.

 

[macbrush]

For me, not only EI works beautifully well (I actually only adapted partially) so I do large water changes once a week.

Another reason (which I hope make sense) is that since my tap water is really soft, and slightly acidic, kind of perfect for a planted tank, I don't want my tank water's parameters go too far from that. I am sure if you neglect water changes for some time, water parameters will shift, most probably in a way that we have no common kits to measure. I figured that if I keep my tank water's parameters as close to my tap water as possible, I am in a much better position to handle any situations or disasters, since I can change as much water as it is needed and as often as I wish, without worrying much.

 

[katana1200]

I just wanted to drop in here and say thank you for the time spent in creating an informative and well thought-out thread, all of you. The last lfs I went into asking questions about lighting said if I tried to get 2 wpg in a tank the only thing I would ever grow is algae. It is refreshing to know there are people who care enough to apply, and share, their knowledge in this seemingly "lost art" of responsible, informed aquaria. Keep up the great work! AC members rock!

 

[edh]

I can help, do you have saltwater or FRESHWATER fish?