Water change schedule

I have 4 Blue Gills in a 100 gallon tank with two Aqua Clear 110's, and 2 Bluegills in a 40 gallon unit with one AC 110. I also have two fancy Goldfish in a 20 gallon unit with an AC 70. They are about 3" long. I got them when they were less than 1" long.

The water to my house uses free chlorine, not chloramines. I treat my change water with PRIME before I pump it in. Fake plants and plenty of filtration in all tanks. Because of my work schedule I change water once every two weeks. The two big tanks get a 60% change and the 20 gets about a 75% change.

One of my Goldfish has a couple of small white spots on its tail. I went and got some stuff for it and the guy at the store said I was changing way too much water at a time. He says that every time I make such a large change I am causing a mini-cycle. He suggests that I feed my fish less and do 20% water changes once a month (I do feed them somewhat heavily but any uneaten food is removed the next day). He also said that the reason my Goldfish tank grows algae is because there is Phosphoric Acid forming in the tank. That made no sense to me.

I lightly vacuum the gravel when I change water, quit using carbon in the filters a long time ago and stopped testing for NO2, NO3 and NH3 because the tests were always negative. I clean the filters once a month using de-chlor'd water. I have the little ceramic stones in there too. I once treated an injured Blue Gill in a 10 gallon tank doing 100% water changes every day. That was a year ago and today the fish is fine.

Am I changing too much water at one time?

I ... stopped testing for NO2, NO3 and NH3 because the tests were always negative.

A test isn't "negative" or "positive"; it tells you the concentration in parts per million.
In order to know what's going on in your tanks we're going to need more information.

1. Go buy brand new test kits for the following:
a) ammonia
b) nitrite
c) nitrate
2. Test your water parameters and interpret the results as follows.

IF: Ammonia is 0 ppm, nitrite is 0 ppm, and nitrate is under 30 ppm:
..THEN: Do not perform a water change. Wait one week and test the water again.

IF: Ammonia is 0 ppm, nitrite is 0 ppm, and nitrate is above 30 ppm:
..THEN: Remove water from the tank via a gravel siphon. Pour in dechlorinated water that is the same temperature as the tank water. Wait 10 minutes and test the water for nitrate again. If still above 30 ppm, repeat. If below, wait one week and test again.

IF: Ammonia or nitrite is not 0 ppm:
..THEN: Your fish will suffer from ammonia/nitrite toxicity. Both should be zero ppm if your nitrogen cycle/live plants (whatever you are using to deal with it) is working properly. If your tank has had water in it for 3 months or more, then at this point you might come to the conclusion that something you are doing is upsetting the cycle.

Without proper test results, there is no way to reach a conclusion. Buy new test kits so that you know the data is not muddled by expired reactive chemicals. Chemicals do have a shelf life, and will go bad after a while, so it's possible that old kits can read inaccurate results after a couple of years. The only way to know what's going on in your tank is to test it and find out.

By the way, the reason that water changes occasionally stress fish and that a 100% water change MIGHT (is not always) be bad is that sometimes the pH and degrees of hardness inside the tank are different than the pH and degrees of hardness that comes out of your tap. For example, let's say that your tap water is a pH of 7 and a hardness of 6 degrees of hardness. If you have a giant driftwood branch in your tank that is turning the water yellow with tannins, then the pH in there could be all the way down at 5.5 or so. If you have a crushed coral substrate then the pH might be all the way up to 8.5 and the hardness up to 18 degrees of hardness. In those instances, the sudden influx of drastically different water would, yes, possibly cause stress to the fish. That is the reason why some people advise doing only partial water changes at a time; the overall pH and hardness swings are minimized, reducing stress to the fish. IF, however, your tank and tap pH and degrees of hardness are fairly similar, then a large water change wouldn't cause as much change in water parameters and therefore as much stress to the fish. Conclusion: Test your tap water and your tank water's pH and degrees of hardness and see how similar they are. Your substrate and tank decorations may or may not be changing the conditions in your tank quite a bit.

Edited by EricaWieser, 27 January 2011 - 10:55 AM.

A less in depth answer. I wouldn't do much more than a 50% water change. 75% on a 20 gal seems way too high. Your large tank can probably handle the 60% due to it's size and stock. 60 is a little high on the 40gal.

I'm not fish keeping expert, but I would settle around 50%. bi-weekly works for me as well, though sometimes it gets pushed to 3-4 weeks. Maybe somemore long time fish keeps will chime in.

You aren't going to start a mini-cycle by changing too much water. I do huge water changes. As long as the new water isn't too much different chemically or temperature wise than the tank water, it isn't going to harm anything.

"I also have two fancy Goldfish in a 20 gallon unit with an AC 70. They are about 3" long. I got them when they were less than 1" long.... One of my Goldfish has a couple of small white spots on its tail."

That's too bad. Is it also flashing/scratching? White spots are probably Ich close to 95% of the time (and you seem to already know that it is), but it's always nice to be sure.

Have you done anything different from your normal routine when it comes to the fishtanks lately? Ich usually springs up from the stress caused by changes, even if they are as minute as stopping the addition of aquarium salt or getting brighter tank lights. I'm sure you already knew this, but it's always good to check if anything might have spurred the outbreak. I think it's a little strange that it's only occurring in one goldfish and not the other.


If that's not the case, then maybe your water is too "new" for your tank when you do change it. Yes, Prime does remove chlorine and chloromines, and several heavy metals, when added to fresh tap water, but it doesn't change the PH or hardness, at least not much. (I'm assuming that you always use the same tap water here.)

In my experience at least, the water that comes out of the tap where I live is like liquid cement -
right out of the tap, it is at 10.4 on the PH scale. However, if I let it sit out the day before a water change, the water drops to a much more agreeable 7.5 PH in those 24 hours. I change 10% of the water bi-weekly, and the water in the tank at any given time is 6.9-7.1 PH from the acids of decomposing materials.

The point I'm trying to make is that even though you always use the same water at the same temperature from the same tap every time you make a water change, the PH of said water is likely much higher than that of the water in the tank, which is more acid because of dissolved organics. This doesn't amount to much when it comes to hardy pond fish like bluegill or most catfish, who are used to such changes in nature. But fancy goldfish (and most fishes bred commercially for the hobby), who are used to a relatively stable PH over time, could be adversely affected by such swings. That's the reason why most newcomers to the fishkeeping hobby are told to make small water changes on a frequent basis. That's also probably why that employee you spoke to said that. (Even if he wasn't sure of the reason why.)

I would suggest the same to you too, but because of your busy schedule that you mentioned, it's difficult to work around. I think you could probably get away with 50% changes in the 20 gallon if you don't mind the profuse algae growth (which is only really because goldfish are little piggies and excrete a ton of poo that ends up as algae fuel). If not, is it possible you could let your water "age" for at least a day before making the water change? I think it could help a little.

In any case, Ich is relatively easy to cure in carbon-, plant-, and invert-free tanks like yours with medication.

(PS: I'm no expert on this by anyone's standards, I just wanted to help somehow. I hope your goldfish gets better.)

Edited by Orangespotted, 27 January 2011 - 06:33 PM.

What you are doing sounds fine to me. Throw away your test kits, I've never owned them in nearly 30 years of fishkeeping (other than pH--you do need that one). If you have the time to change that much water then go ahead and do it. I usually do 90% water changes, but I don't do them as often as I might like to. And don't listen to what folks tell you in fish stores unless you have good reason to trust them. Most of the times they are just blowing smoke, as are many people.

Cheers
Peter

Great answers from everyone. Thanks much!

It seems that nearly every time a situation is discussed the person is reaching for something off the shelf, to sell me.

My water company provides ground water so the quality does not change much, I think. I used to work for the City of Whittier as a water treatment operator and the source there is the same for my water company. The quality does not change much.

The 20 gallon is very easy to change water in so I may try smaller changes a little more frequently.

I will re-read all of the responses and consider the info here. I appreciate it.

...He also said that the reason my Goldfish tank grows algae is because there is Phosphoric Acid forming in the tank. That made no sense to me.

Many municipalities add orthophosphate to the water for corrosion control (keeps lead from leaching out of the pipes). Phosphoric acid is made by combining the orthophosphate with some of the hydrogen ions present in water. It's great stuff for producing algae blooms and can frustrate a lot of aquarists. One of the forum chemists can probably explain the reaction better.

What you are doing sounds fine to me. Throw away your test kits, I've never owned them in nearly 30 years of fishkeeping (other than pH--you do need that one). If you have the time to change that much water then go ahead and do it. I usually do 90% water changes, but I don't do them as often as I might like to. And don't listen to what folks tell you in fish stores unless you have good reason to trust them. Most of the times they are just blowing smoke, as are many people.

Cheers
Peter

In case anyone is suspicious, AussiePeter is not me in disguise, although no one has seen us both together in the same room...

As some of you are well aware by now, I also suggest tossing all test kits. Test kits just make you nervous and cause you to manipulate your water chemistry needlessly. Study up and fully grasp the concept of the nitrification cycle and make frequent observations of your fishs' behavoir.
I don't even suggest buying the pet store pH tests. I use a pH meter everyday as part of my job and can tell you there is huge descrepencies between test methods and even between individuals using the same methods. Manipulating pH with chemicals is very, very touchy and the typical yoyo affect stresses fish more than consistent pH maybe a couple tenths less that the books say you need. My mollies and my blackbanded sunfish thrive and breed in my untreated tap water despite being at opposite ends of the pH scale. The "experts" will tell you it's impossible. My fish disagree.
When in doubt, don't add chemicals, do a water change!

personally, I do 25% water changes weekly. And I only use test kits when things look off in the tank or fish start getting sick. I disagree with Erica's view on only needing to be changed when nitrate shows above 30 ppm. There are many other waste materials that kits don't test for, in general it's just a good practice IMO to regularly water change.

I disagree with Erica's view on only needing to be changed when nitrate shows above 30 ppm. There are many other waste materials that kits don't test for, in general it's just a good practice IMO to regularly water change.

Ooh, yes. CaptainCaveman is right. I often forget to talk about that because in my particular tank setup I don't have to worry because I have live plants and activated carbon. The activated carbon in the filter removes any poisonous macromolecules from the water column, and the plants would fix any heavy metal toxicity that might occur. But yes, for a tank with neither activated carbon nor live plants yes, there is a definite risk of poisons accumulating over time. *nods* I apologize for not mentioning that.

personally i do not do water changes any more. If the purpose of your water changes is to remove nitrates, i've found live plants and/or an algae scrubber will do this for you. I've kept salt water where water changes also added minerals back in the tank that corals needed. But for the purpose of removing nitrates, i have found water changes to be not needed if a functional algae scrubber or live plants are used.