Hi How do I know when my new fish tank has finished cycling so I can add more fish to it. 12 fish are in it now Tank is 130 gallons. So how do i know when i can add more fish?????? Thanks

A tank that size will take awhile. My newest 55 gallon took about 8 weeks. It will depend on what you added to the tank for beneficial bacteria etc. You will get a growth of brown algae first. Once you get the good green algae growing, you will know you are on your way. I think the tank is good once the water gets a sparkling clear clarity to it and all your levels are good. I just achieved that this week. That is a quick explanation of how I think it works and I have had aquariums for 20 years. I would NOT add anymore fish to your tank yet....I know it is tempting but you have to be patient. Robyn will be able to give you a much better explanation :D

KK, I used 100% pond water to start my inside tank. Been three weeks or so, maybe longer, and I haven't had any recycling problems whatsoever. Water is crystal clear.

But how soon, how often, and how much, should I start doing water changes?

Once you have gone a week with zero ammonia and zero nitrite after having previously experienced spikes in those readings, and you are reading positive nitrate, I would say that your tank is cycled. Note that tanks with too few fish may never have registerable ammonia or nitrite so it's hard to say when the cycle is done.

How big are your 12 fish? They're goldfish, right? So, they'll grow and grow and fill out the tank in time without adding many more. It's best to have at least 10 gallons per goldfish in the end.

Johnny, with clear water, good water chemistry readings, and a water temperature near 70 degrees F, I suggest changing about 30% of the water every one to three weeks. How much and how often depends on how many fish you have of what size and how big the tank is. I change 50% of my two smaller aquariums weekly, 30% weekly for the two bigger aquariums, and only 20% of the 20 gallon basement pond only every three weeks for that one (only has two bettas and some tropical pond plants). When you do water changes, be sure to add dechlorinator (even if you have well water like me, I add it to deactivate heavy metals) and maybe some aquarium salt if you use that like I do.

Robyn,

17 gallons, live plants, and one fancy tail.

I have regular city water (no well). How about water changes using pond water?

The pond water's going to be cold so you'd have to warm it up to room temperature. I would just use tap water (we would hope it's cleaner) to avoid adding unwanted bacteria, dormant algae, or other pond organisms. Be sure to add dechlorinator and maybe some aquarium salt (a tablespoon per 5 gallons). Since you just have that one fantail, changing about 30% every two weeks should be enough.

Thanks Robyn. I did a 20-25 percent over the weekend. Then added a few drops (less than cap full) of beneficial bacteria/dechlorinator and small amount of concentrated barley (liquid).

I haven't added salt. Worried about killing my live plants. Remember the last time? Wipped out many of my pond plants. Little nervous anymore.