# Bought an old dirty aquarium and need to change the water



## ruchankaya (Aug 18, 2011)

Hello all,

I just bought a 35g aquarium from Craigslist (yea, I know) and there are 2 young Tiger Oscars, and a sun catfish inside the tank. While bringing me the aquarium, the old owners got rid of 90% of the water. And apparently the water was pretty dirty already. 

All they told me to add some tap water and add some "aqua safe". I started to add some tap water, but then I just wanted to double check if I was doing the right thing, and apparently not. I read some scary comments here and there. I stopped after filling around 25-30% of water. I added a teaspoon of aquasafe (I guess there is now around 10-15g of water inside).

What should I do now? I still need to fill the rest of the tank (70% - ~20g). but the fish were already accustomed to the old dirty water. I read that i could be causing them a PH shock and kill them or some other serious health problems for my fish. 

I feel stuck and I really need some help ASAP.
Thanks for everyone's help in advance.


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## MissPisces (Jun 8, 2011)

Oh, that sounds like a mess... 

First thing you'll want to do is to test the pH in their water and the pH in your tap water. If they're practically the same, you shouldn't have a problem. If they're different, then you can add the water very slowly over a long period of time. There is a big difference in the pH of my tap and tank water, and I usually add the water slowly and it does just fine. 

Secondly, NEVER just add tap water into the tank. Fill a bucket first, then add the conditioner to the bucket and let the water sit until it reaches room temperature. Then it'll be safe to put into the tank. 

The key is not to panic. Panicking can cause you to do things in a hurry, and right now you need to take it slow so that you don't stress the fish (or yourself!). I wish I could help you more, but that's all I can tell you. Good luck!


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## JAREDS (Aug 7, 2011)

I recently moved my tank and what i did was pour the water and chemicals into a bucket them put it in. Often pet shops will do free water tests and when you get the results you could buy either ph increaser or decreaser. I dont know if tiger oscars are hardy or not so hopefully someone else will give their input. However evwn if they where acccostomed to dirty water its not right. Even if they were accostomed and surviving in that kind of water the nitrates and ph and ammonia where probably already all over the place.


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## jrman83 (Jul 9, 2010)

The good news is, if the gravel remained wet the whole time the tank won't need to cycle very much. Optimally, you would have put the fish in a bucket with the old water, filled the tank with your tap, then done a drip acclimation. Once that was completed you could put the fish into your tank with the fresh water and they would be acclimated to it.

Sounds like a rather small size tank for 2 Oscars.


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## James0816 (Jun 19, 2009)

Is a small tank for that stocking.

I always like to recommend to people in these situations (and by "these situations" I mean when they get tanks that the water is just that bad) is to slowly add the new water back in. Just like drip acclimating. You are correct in that draining out that much water and then filling immediately with new clean water can shock them. Even though they are Oscars.


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## glassbird (Feb 2, 2011)

JAREDS said:


> Often pet shops will do free water tests and when you get the results you could buy either ph increaser or decreaser. I dont know if tiger oscars are hardy or not so hopefully someone else will give their input.


I would be VERY hesitant to use pH adjusting chemicals. You need to first invest in a master test kit, which includes a test for pH. Test the water in the tank now, and then test the water coming out of your tap. If they are close, do not go messing with pH up and down chemicals. Fish (most) can adjust to a variety of pHs, but what they can not handle are sudden swings. Those pH products work ok...until they quit, and then your pH bounces to something else! Very rough on the fish, and rarely necessary.

The other toxins in the tank can be tested for with the test kit, specifically ammonia, nitrites, and nitrates. Those will be diluted considerably as you add new water to the tank. Yes, you do need to avoid shocking them, so adding new water slowly is the key. Putting the new water in a bucket, and placing the bucket at a height above the tank (not easy, I know) and then letting the new water siphon into the tank thru an airline is a nice, slow, way to do it.

If you are going to have fish, a master test kit is a necessary bit of equipment anyway. And by the way, good for you to take on fish who need someone to care about them!


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## susankat (Nov 15, 2008)

Never use ph up/down as it causes ph swings that can be just as harmful as fast water changes to a dirty tank.


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## Emphino (Aug 28, 2012)

How did thing turn out. I hope everything worked out for you and your fish.


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## navigator black (Jan 3, 2012)

In a case like that, I would add dechloramine chemicals, adjust the water from the tap to the right level and fill the tank directly. There is a danger of pH shock, but the fish are srewing in ammonia in a small body of water.
Two tiger oscars in a 35 means you have enough aquarium for 1/2 of one of your fish, minus the catfish. It's no wonder the water is dirty. It will be constantly filthy with two predators in there.

I don't know why stores stock Oscars. Well, I do, because they sell. They really should be a fish that is easy to special order, but not on every day display - like dempsies, green terrors and other cichlids that need giant tanks for a decent quality of life.


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## SuckMyCichlids (Nov 5, 2011)

navigator black said:


> I don't know why stores stock Oscars. Well, I do, because they sell. They really should be a fish that is easy to special order, but not on every day display - like dempsies, green terrors and other cichlids that need giant tanks for a decent quality of life.


Sorry to kinda hijack this thread a bit but this is one thing that really gets me fired up, I couldn't agree more with you black, a nice family not meaning any harm just lack of knowlegde is shopping through walmart and see 6 tiger oscars in a tank that can't be more than 10g think "well that'd be cool to have" and then the above scenario has to happen.. if all you had to do is tell the store you'd like one you pay for it and they call you a day or two later to pick it up, that'd definetly save a lot of headaches and the lives of tons of amazing creatures


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## zero (Mar 27, 2012)

MissPisces said:


> and let the water sit until it reaches room temperature.



use your hand thermometer, its quicker than waiting for the bucket to get to room temp and it will be closer to the temp it should be.

im guna hijack too but still no the same subject:

i recently took on two fish (a pleco and a mollie) from a pure filth tank, there was no filter and the guy only changed the water when it turned green. the fish obviously lived in it but the difference nice clean tank water made to them was outstanding! cant remember why i was making this point now, think it ties into what nav said?!

any way i also agree about the oscars, i think maybe its best you give them away or sell them and get yourself some fish that fit in the tank....my oscar went from around 2 inches to well over 6 inches in a couple months and hes still growing!!


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## Crazy (Mar 1, 2012)

Here is a pic of my two tiger oscars in a 75g. The big male is 13" and he is just about a year or so old. If you really want to keep them here is a fact sheet on thier care.

http://www.aquariumforum.com/f51/comprehensive-oscar-cichlid-fact-sheet-34420.html


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