Should I use RO or mineral water for my fish tank due to heavy metals?

Some iron is necessary for a healthy aquarium, but too much can promote algae growth or impart an unsightly yellow or orange tinge to the water. Reverse osmosis (RO) filters are deal for removing mineral and heavy metals from water but they can be prohibitively expensive. Buying RO water from a local market or pet store is also a possibility but not economically feasible if you have a large tank. The best option may be a Polyfilter, which can be purchased in the local pet store or online. These filters will remove iron or other metals/chemicals and must be changed monthly or quarterly. You can also buy a water conditioner that will precipitate out some of the iron which can then be removed by mechanical filtration. An example of just one is Rid Metals (by Kordon). Follow label directions carefully, perform regular water changes and monitor iron levels with a home test kit or by submitting a water sample for testing.

Hi I don't recommend using distilled water in your tank as the "osmolarity" of the water can cause problems for your fish. Either pick up a bottle of water conditioner from a pet store or draw a large bucket of tap water and let it sit for 4 or 5 days. Some of the chemicals will evaporate out when left to sit, but it's not such an ideal option.

Water softeners leave very little salt residue in the treated water. Most, not all, fish *should* do fine in softened water. Make sure you get species that does better in soft water. Use a hardness kit and monitor KH. This parameter is what can affect pH. You can set aside a gallon or two and test it after it has aged for 24-48 hours to confirm it is safe to use. Check the softener unit for a bypass valve. Some units will have one or you can get one installed. Taps/faucets outside may not be in line with the softener, so you can use water from there if necessary.

Fresh tap water can be left sitting over night and any chlorine in the water will evaporate. It can then be used for your tank. Depending on the type of fish you have you should adjust pH and hardness of the water and of course temperature. Your local pet store can help you with that.

If you are getting hard water deposits, use a utility razor and gently scrape the deposit off the glass. When you're doing a water change, if the water level drops below the deposits, use a cloth dampened with plain vinegar and scrub. Be careful to not allow any vinegar into the water. Wipe it well with a clean cloth to remove any vinegar residue and refill. Ideally, the tank should be emptied, sprayed with vinegar, sit for 10-20 minutes then scrubbed or scraped.

You should only have to add dechlorinator when you add new water from the tap. Otherwise the treated water should not accumulate chlorine on its own. I hope this helps and please feel free to post any additional questions.

Reptile water conditioner usually contains chemicals such as Water, Dechloraminating Agents, Synthetic Organic Polymers (Colloids), Chelating Agents, Electrolytes. The reptile conditioner usually also has a chemical that binds calcium in the water as well as a slime protecting agent that is good for amphibians and fish. Aquarium water conditioners (for fresh water fish) contains chemicals such as sulfates such as sodium thiosulfate. Thiosulfate is a Redox reducing agent. Either should be ok for reptiles or fish, however I would stick with reptile conditioner for reptile tanks or mixed (reptile and fish) tanks and for aquaria with fish only I would use specific aquarium water conditioner. The main reason to use a water conditioner is to remove chlorine in water. This, however, can also be attained by leaving the aquarium water fresh from the tap sitting over night. The chlorine will dissipate.