How long can i keep this up for safely?

3 goldfish in a 30 gallon tank is fine. 5 is okay for now but once they start to get big you should need another one. If they're still small, they can be in there for maybe 1 - 1 1/2 years. They should be fine until you find good homes. Thanks for rescuing them!

You should be ok for now, just keep an eye on the ammonia levels. If you have the funds, try grabbing a home tester kit, they even have little ones that you can suction to the inside of the tank for a constant reading.

You didn't mention what sizes the two filters were, hopefully its over thirty, preferably closer to 60.

The Goldie's should be ok for now, since they are smaller and you're keeping an eye on them. Perform regular water changes, at least 10 percent a week. I'd probably switch out the filters every 2-3 weeks instead of every 3-4. Try alternating them , so you don't change both at the same time. Some beneficial bacteria builds up on them and when you throw the filter out you throw the bacteria out. Alternating will be less of a shock on the tanks system.

Best of Luck!

First off what kind of goldfish? If they are fancy it isn't over stocked. Your fish are only 3 inches at best. They can remain in this tank for a good while so no worries. Just stick to your 25% weekly water changes and vacing. What is this 20 +10 rule there is no such thing. When it comes to goldfish and koi you need to take into consideration what type of goldfish it is first then it goes by sq. surface area - filtration. I have been raising goldfish and koi for more than 30 years and I have never heard of such a rule.

Keep up the water changes (up to 50% week) and they should be OK until they reach around 6" long.

Just be aware that if they are common goldfish the 20+10 guidline will lead you astray. Common goldfish can grow to a foot long, think 50gal+20 for each extra.

Dont panic too much, it will take a couple of years for them to grow. So you have time to organise a bigger tank or even a pond for them.

Ian

Though it is overstocked, by keeping up with water changes you should be okay until you can find them new homes. Be sure to monitor your water quality closely.

~If it comforts you, there was a study done where trout were kept in a tight diameter tube with fresh water continuously flowed through it. The fish grew to fill the tune. (Disproving the myth that fish grow to *fit* the size of their environment.) As long as water quality is maintained in ideal conditions the fish will grow. But for the sake of swimming space, and I'm sure multiple weekly water changes don't sound enticing, it would be best to find them homes as quickly as possible.

You can keep em for now, there not that big yet, when they Start, To get big You should maybe Bring em to an, Aquarium if you don't want, Em anymore, Maybe if you still want em You maybe want a bigger tank, But they should be fine for now cause there not even 3 inches yet when there 3 i guess they'll be fine.