Nim- I did post before you, but i hit edit about 3 or four times after. I saw the little somebody posted notice while I was editing but did not stop to click and read, I finished what I was editing. The board did not glitch. I pretty much always edit longer posts a fer times. So my post was really made after yours in terms of my havinbg read yours. I posted again when I did. Incidentally, I see the post times in terms of my New York Time zone when i am logged on
Dang you got me again. I started this post well over an hour ago, I saw a posted was added while i was wtitijng and correcting etc. and did not look. When I posted yours was there - Dang.
There is nothing in your posts to indicate you have soft water. It comes out of the tap at 7, do the test to make it out gas to know the real number.
What the store sold you will put a bunch of things into water that has 0 of them or very little. Ro and rainwater both do. Some tap can as well. However, we have no idea what your tap water contains as we have neither a GH nor a KH reading. My point is what if one of the things that would be added back to water in what you bought is something actually already in your water out of the tap.
But most of this is now taking a back seat to the real problem, you are in a fishless cycle with too many fish for the tank size. Plus the fish you have are not the ones best suited to cycling a tank. This is what killed them the first ones and I am afraid it may again. So there are two reasonable remedies here, get some or all fish out, or get lots of bacteria in, (or a combination of the two).
If you try to keep your current fish alive by doing water changes I fear it may not be possible. Your ammonia levels doubled pretty fast. You may bed doing daily water changes for a really long time and may be doing more than one a day at some points.
If you can find some Dr Tim's One and only, it will cure your problems fastest. If you can find some tetra Safe it should help but is not as good for rescue situations as Dr Tims. The next best thing to do is to try and find people who will donate some cycled media or tank gravel. The more the better. If you can not do any of this than reduce you stocking to the 3 large danios. You might be able to add a 4th but this would be it. Then do a fishless cycle holding the ammonia under 2 for sure but let it hang in the 1- 1.5 range as long as the fish don't mind. When you get to nitrite we will deal with that with out water changes as long as ammonia has come close to zeroing out.
Zebra danios are a suggested cycling fish because they have decent tolerance to ammonia. It should take several weeks to get the tank cycled for that fish load. When it is you will add a new fish that is not more of a waste produce than about 1/4 of the load you now have. This way the mini-spike this creates will not be a problem nor last very long. You will ramp up ever several weeks after that by adding more fish and the being sure that tank handles them before adding more. This is how fish in cycling was always done and should still be.
The need to get out fish is simple, they "exhale" ammonia, they poop waste that turns to ammonia. Even starving them wont turn off the flow. So the only possibility of controlling the amount of ammonia being generated is by controlling the number, size and waste potential of the fish being used. Then one tries to select gidh which are more tolerant of the conditions they are about to undergo.
I would prefer to see you get all the fish out and cycle without them rather than go fish in. No fish are at risk this way. You may be able to ask the store to hold them for credit rather than a refund. Make sure they know you want fish back in a few weeks. You maybe be able to find local fish keepers who would babysit them for you. My point is, the ideal number of fish to use in cycling a tank is as close to none as possible.
The stuff you showed me the link for is crushed coral, but 10 pounds will last you a lifetime in your tank. Ask the store to sell or give you a couple of cups. they porbably hat it in the sw and rift lake tanks. Otherwise find a sw keepers or rift lake cichlid person and they likely can spare a few cups.
You will have to decide what to do from here with the facts at hand.
I would suggest that you only add more of the product you bought if the ph in the tank drops under 5 or when you change water. If 2 spoons got you to 7.0 in about what I estimate is 26-27 gals (102-108 L). 1 spoon for 50L change, 1/2 spoon for a 25 L change should work as a basic guideline in new water.
Interesting. Some stuff puzzles me. To drop ammonia by 50% usually requires a 50% change. You did 25%. It cant be bacteria since you got 0 nitrite before and after.
Unless you anticipated my last post and added some of the ro product in, I wonder why the pH did not budge. Monitor the pH too jik