hardcore water changes - how necessary are they

[zar]

Hi all

i've been trying to learn as much as possible about discus in the past few months, one thing that i still don't understand is why people do these massive water changes. With massive, i mean %50 of water daily or twice daily, on ADULT or semi-adult fish, not fry.
I read that fish excrete a certain hormone into the water which sort of controls their growth, i.e if they detect a certain amount of that hormone they will stop growing or grow slower.
But still, how much of this do they excrete and is there any other reasons for doing these massive water changes on healthy, adult discus that i'm not aware of?
I dont think i'll ever do it but i'm just curious what the reason is.
In a discus setup, lets say 250l tank, planted, canister filter well established with various filter media and lets say 5 or 6 discus in it, doing even 100l water changes every day or ever second day just sounds like a waste to me. it really appreciate it if someone could explain of why 40% or 50% daily or every 2nd day should be done..
thanks

[ILLUSN]

In a balanced planted tank like you've described weekly or 2x weekly changes of 30% would be fine.

if your nuts like some of us, who insist on over feeding for absolute maximum growth then your going to need more changes more often.

Discus need perfect water, a filter can only do so much, the only way to remove the waste is to dilute them out by water changes.

crazy asian brreders us 2x 90% changes daily in unfiltered bare bottom tanks and get phenominal growth out of juvis and adults. mind you some of the breeding adults would be over 20cm in size, so obviously there is something right with their method.

[zar]

yeah doing what asian breeders do is understandable since they often don't have filters in their breeding thanks from what i've read but just airstones.
with the current water restrictions we have i wonder how long or if at all this could be done here at the moment.
i was talking about tanks with established filters, plants that also aid filtration.
you make a good point with overfeeding, but siphoning gravel after feeding could also solve your problem..without changing %50 of the water.
i'm still hoping someone who's a strong believer in the "%50 a day water change along with great filtration needs to be done" will reply with the reasons why he/she does it.

[mistakes r crucial]

We used to change 50%-60% per day but never with adults, only fry and the reason in one word, growth. We had 15 breeding pairs in one system and they used to get anywhere between none a week and 3 times 30%-50% a week depending on what we were trying to achieve with them at the time.
MAC

[Ben]

The idea of doing big WC is keeping nitrates and pollutants low or none.

Back in the day when water was a plenty i had a 200L tank set up with continuous water change/flow. 1000 L per day would run through this tank.

I used it for grow out and could get just attached fry to size of a 50 cent piece in 10 weeks.

[clinny_d]

hey
i read this thread so im going to start doing greater water changes now.
i intend to do %50 at night during weekdays.
then on weekends %50 in the morning and then %10 at night.
what do you think?
ill tell you how it goes
cheers

[ILLUSN]

Do you really think you need it?

unless your growing up a batch of juvis in an overstocked tank i think its a bit unnessary, the frequent water changes can lead to a build up of stress in the fish if your not carefull.

[apistodiscus]

I do agree. No need for massive water changes like that, especially with adult fish. Keep the nitrates below 25 mg/l. If you are feeding beefheart mix you will need to have more frequent W/Cs than if you are feeding seafood based diets.

[mistakes r crucial]

Clinny,

If you have more than just a few tanks and start changing that much water, depending on where you live and your water source, you just might find the local council knocking on your door these days.
MAC

[clinny_d]

hey.
i have only got 1 tank so its ok, and im on tank water.i more have to make sure my old man don't find out lol.
i keep doing water changes, but my tank still looks dusty, any comments?
cheers