Daily or bi-daily water change, percentage changed

[woodenfish]

Am I antomating WC.

I will have two bulkheads for each tank. Both fitted with drain pipe inside tank but to two levels.

One level is the overflow to my garden, to keep at desirable high most of the time. When I fill any excess water will drain to my garden. No valve needed for this curcuit.

The other level is to drain (also to my garden), so the level dictates the percentage water changed. If the level is two-third max, then this will represent one-third WC. There will be a valve that shuts this after enough time, just a few minutes.

What would be a best plan?

Half everyday

Half every other day

one-third every day

one-third every other day

etc

What is the most reasonable compromise between wanton waste of water and best health for my fish?

I had thought of using just one level, the top level, and just fill continuously for a few hours every day or every other day. Now I think that any WC plan that does not first drain the old water is wasteful and inefficent.

[Apistomaster]

The best option would depend on the size of your Discus tank and its normal population. If you stock it conservatively (1 discus/10gals) 50% x 2 week water changes will give good results. If you want to push the envelope and stock at extremely high levels 100%/day may be appropriate. Even twice that will allow for very high stocking levels.
Depends on your goals, I suppose.
Experiments with rainbow trout consisting of confining a single fish in a narrow cylinder with a volume of one gallon but supplied with a constant inflow of fresh water resulted in trout that grew as large as control groups pond raised with flow through water supplies.
It was just to see what is possible but the practical applications are low.

[Seecher]

The best option would depend on the
size of your Discus tank and its normal population. If you stock it
conservatively (1 discus/10gals) 50% x 2 week water changes will
give good results. ....

My question is why?

What were the water parameters prior to 50% water change?
Nitrate levels too high?

Is the 50% water change twice a week with one fish per 10 gal.
based on measured conditions of the water which indicated that
this water change was necessary, or rule of thumb handed down
from one hobbyist/breeder to another without any water testing?

Thanks in advance for your reply.

[Don Trinko]

This is one of those things that the only thing 2 out of 3 discus keepers will agree on is that the third person is wrong.

I'm no expert but I asked similar questions when I started keeping discus. Right or wrong I test for Nitrates and try to keep them near 5. When they start to climb I either change more water or more often. I prefer not to change more than 33% at a time just incase something goes wrong with the water.

I talked to a discus breeder who indicated that it is not neccisary to do 100% water changes to "grow out" quality discus. I don't think it does any harm if your water is OK. He indicated that changing based on nitrates was a good way to decide when you needed a wc. I think he is one of the sponsers of this web site but I preffer not to mention his name here. Don T.

[Apistomaster]

Don was quite correct.
It has been empirically established that discus do best with some kind of routine water changes. The main benefit is that you are exporting, minimizing and diluting the variety of organics that accumulate. Discus respond very positively to these water changes but Discus keeping is an art as much as science so there are always gong to be different opinions on what is best or good.
No water changes are never good.

One reason for the water changes is that discus evolved in an environment where most of the planet's fresh water in rivers flows.
Some attempt to reproduce this is only common sense.

I personally think for most home Discus aquariums that daily 100% water changes are examples of over kill. IMO at least 50% a week is enough for most home aquariums and this applies to all aquariums. The fish will always do better if you have some kind of regime of water changes.There is a life outside discus keeping but some like to change water more than others.
I settle for two 75% changes per week based on my relatively high stocking levels.

[White Worm]

For someone with just a hobbyist vision with low stocking levels...I prefer to do 1-2 75% w/c's in a 7 day period. I think the larger changes spread out do more than small changes every day. It also depends on your filtration. With my new canister filter, I find my tank staying much cleaner much longer. I still stick with my water changes though because I can actually see the difference in their appearance and behavior after a nice large w/c.

[Apistomaster]

For someone with just a hobbyist vision with low stocking levels...I prefer to do 1-2 75% w/c's in a 7 day period. I think the larger changes spread out do more than small changes every day. It also depends on your filtration. With my new canister filter, I find my tank staying much cleaner much longer. I still stick with my water changes though because I can actually see the difference in their appearance and behavior after a nice large w/c.

And I think you are right.

[kaceyo]

To answere part of your question, much of what is being removed by WC's isn't measurable by any test available to hobbiests. You can measure nitrates, the end product of your biofilters actions, and thats why people use it as an indicater of when to do WC's. But there are dozens of other compounds building up in the water as a result of food decomposing and being processed by the fish, the many chemicals breaking down and fishes metabolites entering the water. These can't be filtered out so the only way to remove them is through WC's. Discus are much more sensitive to this polution than your average aquarium fish so, in order to thrive at their best, we need to replace this poluted water with fresh more frequently. Replacing it all as often as possible gives you the best results. So you have balance what your willing to do with what your goals are and factor in the bioload etc, etc, and come up with something that works for you.

Kacey