Water changes & wait periods when stocking
I got a fundamental question --
When should I change the water in my tanks? My 20 gallon has been running since May, 2011. However, I notice that the fish seem to look more comfy when I change 25% of the water twice a week rather than 25% once a week. According to the guy at PETCO I should be fine with a 25% water change once a week. (Hence the question).
For my 55 gallon, is it better to change 25% once a week, or 10% twice a week? Can more water changes help ease the ammonia etc. spikes once new fish are added. Or is it better to just stick to fewer fish at a time? (say 6-8 Harlequin rasboras on the 55 gallon).
Also, is it better to wait for 2 weeks instead of 1 week before adding new fish (like I have been doing).
On my small tanks I like to do 2 a week or more, my big tanks I only do once, if not for time and paying for water I'd probably do more.
How long has the 55 been set up? Yes the water changes will help the spikes. I'm sure someone will go into full detail for you.
If you think of it, the water change is actually diluting the 'contaminated' water. So very simply, a weekly water change of 50% is more dilution that two water changes weekly at 25%.
I'm convinced (Byron kudos) that a weekly 50%~ water change is the ticket...And my water change is gravel siphoning, complete glass cleaning and sometimes servicing one of the two filters.
This is working very well for me. The water is very clean and the fish seem very happy.
I'd like to separate the issue out into two components so it is perhaps easier to understand.
First, with respect to the increase in ammonia when adding new fish; unless you do 50% water changes each day, the water change will have little benefit on the ammonia spike. The ammonia rises steadily, and this immediately affects most fish. However, the good news is that live plants will assimilate this also immediately. So will nitrosomonas bacteria once it multiplies, and that takes between 12 and 32 hours. But that is still faster than your water change 2-3 days later. You can read this in more detail in this article that I wrote to explain how all this is connected:
To the second issue, water changes generally. This is the only way to remove "crud." No filter will. "Crud" is my term ("borrowed" from David, the Editor of TFH) for urine, pheromones, chemicals released by fish and plants, etc. that remain in the aquarium until the water is removed.
We have gone into this in a couple of previous threads [AbbeysDad was referring to those in his comment] but to summarize, the more water you remove at one time, the more "crud" is removed and less remains in the aquarium. The water change should be substantial, I suggest 50% of the tank. Once a week is do-able for most of us [one could argue that if it isn't, you have no business having fish;-)]. If you can manage twice a week, even better. If you could do it every day, better still [there are other issues here of course, but I won't go down that road]. After all, fish in nature live in the same water for a second. In our aquarium they are forced to exist in the same water until we do a water change. Discuss breeders do 90% water changes in fry tanks several times a day to keep the fry healthy. Water changes cannot harm fish--unless the aquarium has been allowed to deteriorate in the first place.
Byron, I question the logic here. "fish in nature live in the same water for a second" even in a river this is questionable since other fish and river life have polluted the water upstream - not to mention more stagnant ponds, ditches and tanks where our aquarium water is likely significantly cleaner with less 'crud'. Maybe we might see measurable improvement (unsure how to quantify) with 50% changes twice weekly - however, we reach a point of diminishing returns. If we have crystal clear water and healthy, happy fish, we should ask what would really be gained by daily water changes? To bad we don't have a simple measure of water quality to know the 'crud factor'. What is interesting here as well is the other variables such as tank size, bio-load, real plants or not, method of water change (gravel siphon or not)...all play a role in the true water change requirement. :-)
Thanks for all your input. I'm planning to do water changes twice a week from now on. I can...I just didn't want to do it if it wasn't necessary. Now that I've got my routine down, I'll stick to it. Its just unfortunate that the LFS sometimes gives wrong info....or I guess they wanted me to buy more fish after they had croaked :evil:
Just wanted to add...if not quarantining any new fish I would wait a couple weeks between fish additions to watch for any disease. There's still a big risk of contaminating the whole tank.
Any crud produced by the fish is immediately dissipated throughout the water to the point where it is basically undetectable. Other fish can swim away from it. The same water never flows over the fishes' gills from breath to breath; fish swim upstream, so the water passing through their gills is behind them always. This cannot be replicated in an aquarium.
Crystal clear water is not necessarily "clean" water. Water in countless Amazonian streams is so murky you cannot see your hand held in front of you, but it is extremely "clean." Cardinal tetra are believed to have the vivid neon stripe as a means of being able to see each other in the opaque water in which they live; I believe I have posted a video of a shoal of cardinals and all you can see are some neon lines moving about for about a foot or two in front of the camera. But aside from this, crystal clear water in an aquarium can be toxic with all sorts of substances that are not visible, and many cannot be tested.
The crud remains in the water. It is true that live plants will handle it, but this is a slow process and for this to work one author suggested no more than 6 neon tetra in a 55g aquarium that was very heavily planted. This setup could go without any water changes. But this is why the more plants one has, the less water needs to be changed (depending upon fish load). Which is why I can manage with weekly 50% water changes; without my plants, I would need to do much more than this to achieve a similar state of "clean."
I got another question:
In my 55 gallon, whenever I do a water change, one or more of my glowlight tetras die. I am not sure what is going on! I did a 10% water change yesterday night and the water parameters are (as of 30 minutes ago):
Ammonia, nitrites & nitrates = 0 mg/L
pH = 7.8
hardness = 150 mg/ml
I got the water tested at my local Petsmart...the units are differnet from ppm (which is on my kit), but I suppose they're equivalent. They did the water test when I returned the one dead fish.
I got 8 glowlights on the 20th of July. Now I just have 3 left! I have noticed that on one of them, the face got opaque as if it was wearing a mask...the rest of the body is transparent, which is normal (except where they have the stripe).
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