Why Are Water Changes Necessary?

[Keith Perkins]

You can still keep them, they just won't reach their potential with only 2 WCs a week.

[cameron]

You can still keep them, they just won't reach their potential with only 2 WCs a week.

Yes and this is what I was curious about. The nitrate levels should remain fine with 2 WC / week (<5) and ammonia and nitrite should remain 0 so I am wondering what makes this necessary - is it just a tried and true thing and its true for a variety of factors like those said above or is their a very specific reason that makes it necessary.


And as a separate question would 80% water changes twice a week work. Because a 80% water change twice a week would result in only 4% of the water being leftover every week (0.2 * 0.2) while a 35% day water change would result in 5% of the water leftover (0.65 ^ 7), so wouldn't the 80% twice a week water changes be noticeably better. (Though 70% twice a week would result in 9% of the water being left over)

[Madaboutdiscus]

Truthfully if you can't do daily changes you really need to stick to adults. They don't require as many changes. With adults you'd be fine with 2-3 times weekly 80%. Adults are sensitive to water quality but juvies are 100 times more sensitive. They won't do well without daily changes.

[discuspaul]

Truthfully if you can't do daily changes you really need to stick to adults. They don't require as many changes. With adults you'd be fine with 2-3 times weekly 80%. Adults are sensitive to water quality but juvies are 100 times more sensitive. They won't do well without daily changes.

Agree.
You said you wanted juvies because that's all you can afford. Not sure what size juvies you're talking about Cameron, but if they're 3" or less (or even 3.5" or less) - 2 WC's a week will very likely result in them growing out to maturity (adult) @ only 5" or likely less. More importantly, one or more may turn out 'stunted' which is obviously not what you want.
This is tried & true stuff.
As said by "Mad.....", get adult fish (even if that means waiting while you save more money), or get as near adult as you can afford - should preferably be not less than 4.5" -5".

[OC Discus]

Cameron,

Since you are trying to understand the "reasons" for frequent water changes, it is generally accepted that to grow "juvis" to their potential +/- 8" you need to feed them very heavily for the first year or so. Most experienced keepers feed young ones 5 times a day or so. Others like John N, feed twice a day, but they overfeed so the fish get all they possibly can eat in 30-60 minutes.

Now is where the need for the water changes comes in. If you are feeding the fish like this, the left over food and waste will quickly foul the water and your levels won't stay perfect as you suggest. If you have substrate, bacterial issues can quickly develop. If you have other types of fish, cross contamination from parasites can occur because the fish are weakened by poor water quality.

If you don't feed the fish as stated above, they won't grow to the desired 7-8". So, like Paul said, you might get by with smaller feedings and fewer water changes, but you will end up with smaller fish. Most of the members posting here are aiming for maximum size and health.

[cameron]

Ok so I think I understand the reason now. When you buy juvie fish if you are interested in getting them to their full size of 8"+ then you need to feed them a lot. And if you are interested in feeding them a lot then you need to keep the tank clean because a lot of food could hurt your water quality.

Thanks everyone!


So now I have two more questions.

1) If I don't do as many water changes as recommended and the fish only grow to 5-6" then will the fish be hurt / stunted / experience any problems with their lives because of this.

I am not interested in paying the amount for 4-5" fish not just because I can't afford them but also because I don't want to pay so much for a group of discus especially when I don't have experience keeping them.

2) And secondly if I do for example three water changes a week would that work better. Should I want to take a group of 6 juvies and grow them out to a nice desired 7-8" size with 3-4 daily feedings would for example 3-4 weekly 75% water changes work?

[William Palumbo]

First off most Discus will not reach 8" in size...not even the so called "Giant" strains. They are out there but the norm is 5"-6" no matter how much water you change or how many times you feed them. I change my water 3X a week. If you put 6 juvies in a 55g or bigger, 3X a week water changes will be fine...Bill

[OC Discus]

Adding to what Bill said, filtration plays an important part in water quality and fish growth also. Most breeders are using sponge filters. Sponge filters keep all the waste in the tank, near the fish. So this necessitates cleaning the tank daily or at least more frequently.

If you have more extensive filtration with adequate bio media, 2-4 times what is rated for your tank size, it will handle your bio load longer between water changes than just a sponge. Your fish will be more healthy and grow faster with your proposed water changes than if you just used a sponge filter and changed the same amount of water. A purigen reactor could further contribute to their health and water quality.

[cameron]

I don't think I'm going to use the purigen reactor but do you guys think that dual Aquaclear 70s w/ dual sponge filters would be noticeably better than a single Aquaclear 70 w/ dual sponge filters.

So if I only do 3 water changes a week will the fish be hurt at all because I don't want them to get hurt.

And will 3 water changes a week be noticeably better than 2 water changes a week.

[discuspaul]

Cameron, if the fish don't reach their potential growth, or are stunted, they're not ailing in any way, nor facing any harmful effects- only their size is affected.
If they're well cared for they'll be healthy & remain that way.

I agree with Bill that with 3 large wcs a week, 6 juvies in a 55 gal bb tank should be fine - but keep in mind that the possibility still exists that one or two could develop to be stunted, whether you do 2 or 3 wcs a week - I don't personally believe there's much of a difference between the two, but more wcs have got to be somewhat better for the fish.

Stunting means they won't generally grow much beyond about 3" - 3.5" or so, and their eyes will be out of proportion to their body, but if that doesn't bother you, then go ahead.

Personally, I've not had a stunted fish for as long as I can remember, and if I had, I confess I'd be a little ashamed to show it to other discus-keepers, who would likely know it didn't receive the care & attention it should have had while growing out.

[OC Discus]

Cameron,

You will get many opinions about what filters are best. My experience with sponge filters is they need to be cleaned daily because they draw an accumulation of food and waste that will look bad if not cleaned daily, and possibly impair the function of the filters. Is there a reason you are set on that type of filter? If I were set on "not" cleaning daily, I would look for filters that would draw the waste out of the tank, if for no other reason than appearance sake. If its in a fish room it may not matter. But if it is a display tank in the family room, a good canister or Hang On system might be better.

There are some threads on sd titled "what are the best filters" that might be a good place to start. Since the fish are small, you might start with one good filter and add another as they get larger. Im not going to recommend any brand, but just some things to consider.

I don't think I'm going to use the purigen reactor but do you guys think that dual Aquaclear 70s w/ dual sponge filters would be noticeably better than a single Aquaclear 70 w/ dual sponge filters.

So if I only do 3 water changes a week will the fish be hurt at all because I don't want them to get hurt.

And will 3 water changes a week be noticeably better than 2 water changes a week.

[rickztahone]

Yes and this is what I was curious about. The nitrate levels should remain fine with 2 WC / week (<5) and ammonia and nitrite should remain 0 so I am wondering what makes this necessary - is it just a tried and true thing and its true for a variety of factors like those said above or is their a very specific reason that makes it necessary.


And as a separate question would 80% water changes twice a week work. Because a 80% water change twice a week would result in only 4% of the water being leftover every week (0.2 * 0.2) while a 35% day water change would result in 5% of the water leftover (0.65 ^ 7), so wouldn't the 80% twice a week water changes be noticeably better. (Though 70% twice a week would result in 9% of the water being left over)

I'm going to put this in the easiest way possible:

People here (including me) will tell you to do more WC's. Why?, because when we grow out juvies we feed A LOT!!! As in, 3-6 times a day. You mention that your nitrates and everything stays low now, but can you possibly think that feeding discus (some of the messiest fish ever!) 6x's a day wouldn't mess with your parameters at week end? Many here feed beefheart, a very messy feed as is.

So, simply put, we do a lot of water changes because we feed too much to grow the heck out of our discus.

Can you do less water changes and feed less? ABSOLUTELY. Will you have huge discus? Probably not. But you will have some decent sizes juvies, and with your next batch you will want to have bigger discus and THEN you will start doing larger water changes to achieve that goal.

[afriend]

I believe that one significant reason for making water changes is to reduce dissolved organic compounds (DOCs). These come from two sources: uneaten food and feces. DOCs in the water increase bacteria and parasites and this results in unhealthy conditions for the fish.

A product called Purigen absorbs organic compounds, and when combined with water changes, can further reduce DOCs to a level lower than with water changes alone.

Paul

[discuspaul]

I believe that one significant reason for making water changes is to reduce dissolved organic compounds (DOCs). These come from two sources: uneaten food and feces. DOCs in the water increase bacteria and parasites and this results in unhealthy conditions for the fish.

A product called Purigen absorbs organic compounds, and when combined with water changes, can further reduce DOCs to a level lower than with water changes alone.

Paul

Very appropriate post.
Cozy Keith mentioned this very thing (bacteria) in general terms in post # 14 on Page 1.
And yes, Purigen will help to reduce DOCs.

[Kiang]

Sorry to intercept the post.

I just got 3 3inch juv discus to com with my 3inch altum angelfish.

The grow up tank setup is a 25gal BB tank with 80% wc and 2 x feeding daily.

Will the huge wc regime affect the altum angel?



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