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chemicals when doing water changes

25 9:22:06

Question
Hello, I am new to aquariums, and I'm having a hard time, and I get so much conflicting information. I have a 10 gallon tank to which I have added a total of 3 platies and 2 mollies. I added 2 platies, waited 2 weeks and added 1 platie and 2 mollies - total 5 fish. I could not get the water clear, and I have .25 - 1.0 of ammonia each day. Petsmart told me to leave the tank alone. Petfish.com says to do a 25% water change until it is down. So, I've been doing 10 - 25% water changes almost daily. I've tried using Amquel+ to bring down the ammonia, and I use it because supposedly it does not cause false readings for ammonia, but it does not seem to do any good anyway.  I always use reverse osmosis water for the tank - not tap water. 1) do I need to add a water conditioner? 2) when I remove water and then replace it, should I only add chemicals based on the replacement amount? example: aquarium salt - if I take out 25% of the water, I only add enough salt for that water change. That makes sense to me because salt does not "go away." But, other chemicals say nothing other than to add X amount per 10 gallons of water. Specificly - I have been using Cycle to try to get the biological cycle in motion, which is hard when the water is always "new". Example. I ended up doing a 50% water change yesterday because the ammonia was 1.5. Since I had already added Cycle, should I put more in, which in this case would be 1/2 the dose listed on the bottle for a 10 gallon tank? And, I have been using a water conditioner - Proquatics. Should I only put enough of that in (would be 1/2 dose) to cover for the water removed rather than the dose for a "10 gallon tank"? I've tried using Amquel+ but it does not seem to do anything to bring down the ammonia. Bottom line question. When adding chemicals after a water change, should the dose be based on the amount of water being replaced? Thanks so much!! I'm trying SO hard to keep my little fishies happy and not kill them. Petsmart clerk told me to leave the tank along even though she said the "ammonia level was off the chart". Well, geez, my fish would be dead in 1 day like that. Help!! Any knowledgeable advise would be so, so appreciated! Thanks.

Answer
Wow! You've given me alot to work with. I'll do my best to address everything. Feel free to ask me a followup if everything isn't clear.

The first thing I think I should cover is the bacterial cycle. Fish produce waste in the form of ammonia. Ammonia is very poisonous to fish, it can be deadly at levels of 0.05 mg/l. Bacteria in the aquarium will literally eat the ammonia and produce another chemical called nitrite. Nitrite isn't as deadly as ammonia, but its still not good for fish. Another type of bacteria will eat the nitrite and produce nitrate. Nitrate isn't all that bad for fish, but it can be bad if it gets too high. In normal aquariums there is nothing that will remove nitrates, so you must do partial water changes to get rid of it. The Cycle biological treatment is almost worthless in my opinion. I wouldn't waste my time with it.
When you have high ammonia, it will naturally go away, but that could take upwards of a month. Water changes will dilute the ammonia, but it will never get rid of all of it. Water changes will speed up the amount of time it takes for the ammonia to be taken up by bacteria, so it would be a good idea to keep changing the water every few days. I would only change 2-3gallons at a time (20-30% is a normal amount for water changes). Depending on the chemistry of your tap water, you may be able to do water changes with it. You don't need to do water changes with RO, in fact with the fish you've got, its not a good idea to use RO. Its too soft, you'll see pH swings and it may the the root of your problem. You should get your full water chemistry tested. Find out pH, Hardness (KH), ammonia (NH3/NH4), nitrite (NO2), nitrate (NO3). Once you get these values tested, ask me a followup question, and I can help you some more.
The cloudiness you're seeing is likely a bacterial bloom. (sort of a grey/brownish color). Bacterial blooms occur when the bacteria are unhappy, usually from poor water chemistry. The cloudiness should clear up before the ammonia goes down.
The chemicals that are used to treat high ammonia will not remove ammonia from the tank. Adding these will "detoxify" ammonia, but you will still see high levels. When you've got as high ammonia as you're seeing, its not a bad idea to treat with these chemicals while you're working on the problem. You only need to add chemicals for the water you are changing. So, if you change five gallons, treat the tank for 5 gallons.
Lastly, you need to figure out why the ammonia is so high. Brand new tank? Its very normal to see these high levels before the bacteria catch up with biological load. Feeding too much? Never feed more than your fish can eat in 3-5 minutes. If food sits on the bottom of the tank after 5 minutes, you've fed too much. It would be a good idea to cut down the feeding while the ammonia is high. Every other day is fine for a few weeks.
Hope this helps,
Good luck