water change frequency/ tank size/ discus size help

[ziku1]

I have 450litre tank+200 litre sump capacity
i have read in the forum that to grow big 7-8 inch discus i will need to do 50% water change every day
so do i really need to do 300litre water changes everyday

can I do less water changes while they are small and slowly increase frequency as they get bigger or vice versa
I have a 6ftx18inchx20inch wide tank so is it possible to grow them to the 7-8inch mark with a tank this size (im worried about the width)
I will be keeping 6-10 discus bare bottom tank, no tankmates

[ziku1]

also i am not worried if it will take longer to grow them big
just as long as they rach the sizes

[taksan]

Do 3 50% WC's per week
That wil lbe fine

[ziku1]

so do i do 50% 3 days a week
even when they are juvies as they will create less waste and eat less

[samir]

the more water you change the faster they will grow depends on how many you can manage. optimium would be 50% change twice a day, realistic would be what Tanksan recommended. feeding them 6-8 times a day helps too. :D

[ziku1]

how much w/c do you do samir

[JNS]

Sorry to all who posted advice...but I just cannot buy this.

I spent years NOT keeping discus because of advice like "change 50% of your water so many times a week".

Fishkeeping is an old hobby, and there are many myths around it...I think discus keeping is one of the worst for this - mainly because discus are for the advanced hobbiest and it thus gets shrouded in the exotic and mythical.

So, is there some sound science behind the advice of doing HUGE water changes to get your discus to grow faster? Has someone actually done side-by-side experiments in controlled conditions to prove this. If so, I would certainly like to hear it.

BTW, I have a 200L planted tank; change 30L water once a week; and my discus are doing fine.

[samir]

for the fry i do 50% everyday. for adult 50% twice a week.

[FishLover]

Jack Waterly did the side by side experiments in controlled conditions.

He feed them exactly the same amount of food, same temp and same pH, one had three WC per day (yes he did W/C 3:00am!) and another had 2 per week.

After one month, the size are almost double in the more WC tank than the less WC tank.

[ziku1]

what percentage w/c did he do

[FishLover]

In order to get the exact numbers, I checked the back issue of TFH mag and here is the controlled test:
4 weeks of controlled test using the same number of frys in two tanks, one tank is 12 times bigger than the other. Same pH, food and everything. The bigger tank has a sponge filter, the small tank only has an air stone.

Here comes the difference in W/C:
the lager tank get 40% daily
smaller tank get 6 to 8 90% daile(at least one at 3:00am!)

After 4 weeks, the fry in the smaller tank are nearly twice as big as the bigger tank.

This was published in early issue of TFH mag and Jack said it again in June 2006 issue when answering the reader in the Ask Jack section. The reader had almost the same question as you did and I think Jack's answer was very good to the point.

Water change does matter if you want to grow them big and happy.

[JNS]

I won't dispute the value of water changes, but that experiment was not "exactly" the same.

Tank size was different, and filtration was different.

A true scientific method would use EXACT same parameters for everything and vary only frequency and/or water change amount.

I will buy in the argument that regular water changes are good, and more frequent the better, but how frequent and how much? What is optimal? Is it necessary to change the 50% of the water 3 times a day, or will 50% once a day give the same (or almost the same) results? Can you even go less than that and get the same?

Sure, the more maintenance on an asset you do, the less likely it will fail and/or give better performance, but there comes a point where too much maintenace adds very little or no value to the objective. Sounds like no one has really worked that out.

Perhaps better advice for a beginner is to tell them minimum, and then let them know that if they want better "performance" (in terms of growth, breeding, etc), they will need to do more.

Breeders and people with a commercial interest in their fish will be willing to put in hard yards, but others who just want healthy, happy fish do not need to go to such extremes, and telling them to do so may discourage them from what is a very satifying and rewarding hobby (discus keeping).

Just my 2cents....

[Merrilyn]

This is a very interesting subject and I've read lots of differing opinions.

If you're asking what is the optimum to get growth rate, then changing water as frequently as you can manage is the way to go. But if you're asking, what can you get away with..........then that's a very different thing.

I think in this very dry country of Australia, where water restrictions are in place for most of the year, it would be irresponsible to do huge daily waterchanges on all our tanks, much as we might like to.

I do change 50% of the water daily on my fry tanks, but they are generally small tanks, of about 80 litres. Larger tanks with adults get twice weekly water changes of 50%, and the nitrates are always low, especially in the planted tanks where the plants are growing vigorously.

Keep an eye on your nitrate readings, they should never go over 10 on a discus tank. If your readings are constantly over that, then more frequent water changes are called for.

[FishLover]

JNS,
I think Jack was trying to proove one point in the test:
Bigger tank with less WC is worse than small tank with more WCs. That's what most people are telling him that they get a bigger tank so they don't need more WCs.

Anyway, I agree with you there is a cross point that the breeders and average folks differ in terms of WC. Actually, feeding is different too. The difference comes from the goals of keeping the fish.

The breeders want to grow their stock fast and big so they can get top $$ quickly.

The average folks like me just want pretty looking and happy fish.

That's why I don't use beef heart to feed my discus and I only do 40% WC per week. Beef heart will grow your discus fast but also mess up your water quickly. Tell you the truth, I really don't like it since it is not a nature diet for the Discus anyway. The breeders use beef heart for the reasons such as fast growth and cheap price. They use more WC to take care of the nasty things associated with beef heart. Me? Since I don't have time to do daily WC and don't have to feed 200 discus each day, the price of feed is not a major concern. I will be more than glad to exchange the price with less WCs.

The thing is, my Discus look smaller than the breeder's for the same age and I don't really care since they look happy and colorful to me. I don't really care if the grow up to 8" or not. 5" to 6" is very good for me.

The way I look at is that you decide what you want with the discus first, and that will in term decides what you have to do with WC and feeding.

[EYEShurt]

fishlover just out of intrest what do you feed your discus