I have (1) 55 gallon Marine salt water aquarium that requires weekly water changes and monthly filter maintenance.
It needs weekly water changes to keep nitrates between .1 and 5 because marine fish are more sensitive to nitr
ates, whereas cold or tropical fresh water fish are not as sensitive.
(2) 55 gallon rift lake aquarium (one of them is home to the blue fish you see in the pic to the side).
(1) 55 gallon tropical fresh water aquarium
(1) 40 gallon tropical fresh water aquarium (home to only 2 Angle Fish)
(1) 30 gallon cold fresh water aquarium (4 round bellied goldfish)
I change fish around in my tropical freshwater tanks. I do a lot of trading so that number is subject to change (lol) I know it's a lot of tanks, but I see my aquariums as living art...
All my freshwater aquariums only require new filter cartridges and (1) 20% water change a month.
This is because I don't over crowd the tanks, I have a good understanding about water chemistry and the fish I keep, and my filters bio-sponges and bio-wheels have good strong beneficial bacterial colonies established in them.
The bacteria colonies is what converts all the waste into a non toxic form.
The non toxic form is called nitr
ate.
It is only non toxic to freshwater fish if kept under 75 ppm. (I never let mine get that high though) I feel that a nitr
ate reading over 40 deserves a water change.
The good bacteria that live in my filters bio-sponges and bio-wheels do all the hard work for me.
All I have to do is change the dirty cartridges and remove the nitr
ates by preforming water changes.
Also, I have a very handy device called a Python that pumps the dirty water out, then with a flip of a switch, it puts fresh clean water back into the tanks.
I spend about 1 hour every month cleaning my freshwater tanks - thats it...
(now my marine saltwater tank is a different story - it's not so easy because I use buckets and requires more time - about 30 minutes to 1 hour a week)
In nature, nitr
ate would be consumed by plants and other organisms like algae; however in an enclosed aquarium environment, we could not keep enough plants and algae to consume all the nitr
ates, so we remove them by water changes.
In all honesty, you have overstocked your tank...
If some of the fish are not given proper homes, you will continue to have problems with water clarity, sick fish, and eventually dying fish.
Big round bellied goldfish are not physically able to swim in strong currents. I'm sure that the (2) 55 gallon filters you have on your tank is finally taking it's tole. They will soon be out of strength and give up the fight to swim.
Koi are aggressive fish that get huge in size. They will pick on weaker fish until the weaker fish die.
Koi and comet goldfish belong in ponds because of their size and the amount of waste they produce.
Here are a few pictures of Koi:
Attachment 2964
Attachment 2965
Attachment 2966
As you can see, you will need much more than another tank if you decide to keep these fish.
If a lot of fish is what you desire, your 30 gallon tank would make a wonderful home for 30 non aggressive tropical fish like Guppies, Tetras, and Mollies just to name a few.
I hate to be a barer of bad news, but with the type and the amount of fish you are keeping in your 30 gallon right now, your new hobby is going to turn into your biggest job and you will struggle to keep the water clean.
Goldfish are messy and a 30 gallon can happily give a home to 4 or 5 full grown round bellied goldfish. (I have 4 full grown ones in mine).
Also, you may not need to add aquarium salt.
Freshwater aquarium salt raises the alkalinity (KH) in water.
Your tap water may already have a stable KH and salt would be unnecessary and possibly risky.
If you don't mind, could you test your tap water for GH, KH, and PH (low range). This way we can know the readings of your tap water before it goes into your tank.
Put some tap water in a cup, wait 15 to 30 minutes then test it.
We will use that reading to compare to your aquarium water reading.
This way I'll have a better idea about what is happening with the aquarium water and what should and shouldn't be added.
A lot of times, new fish keepers will take a little advice from a lot of different people and try to use it to solve their aquarium problems...
Unfortunately, this is not a wise decision.
There are many different fish keepers that use different systems that work for them.
When you take bits and pieces of a lot of different peoples advice and try using them for yourself, it usually fails.
This is because one method of fish keeping may not be compatible with another.
Plus, Joe Smoe at the fish department may not be taking into consideration your tanks specific needs. I found out the hard way long ago that employees at fish departments don't always know what their talking about (Walmart and petsmart employees are the worst).
Where do you buy your fish and get advice from?
You have to come up with a system that works for your tank...
First step in doing this is to understand your water (tap and aquarium).
Second step is to understand the nitrogen cycle or "cycle" and "beneficial bacteria"
After your tank has stabilized and you have a system you use for maintaining it, you will not have to do so much work and water tests.
Do you need help understanding the nitrogen cycle?
I want you to be able to enjoy your new hobby - not hate it...
So lets work on getting this right and finding a system that works for you and your tank... I'm here to help...