New 20 Gal, Problems

[charlotte!]

I've had my 20 gal about a month and it's finished cycling (fishless cycle with dead shrimp). Wednesday I went and got fish for it. 2 male guppies, 2 female guppies, 1 boesmani rainbow, 5 ghost shrimp and 1 balloon belly molly.
Before this I got 3 cherry shrimp which died in an hour. The ghost shrimp lasted more than an hour but when I checked in the morning all 5 were dead.
One cobra guppy was acting scared when I first put him in. The other 3 were staying together and he was by himself at the bottom. Yesterday (Thursday) when I got him he had major chunks out of his tail, and this morning now it's about half gone. I put him in a separate cup floating in the tank because I have no clue what to do. Do you think he's fine to swim? and which fish is more likely to be biting him, the molly or rainbowfish (or both, they both seem to have potential)? I thought they would all be fine together but apparently not. Do I need to separate them or will they calm down? I'd rather not have the guppies living in fear so if this is going to be a constant problem I guess I need to figure something out. I've heard getting another rainbowfish to go with this one might help distract him (or her, I dont know) but I don't want to get another one and have double the trouble. The molly and the rainbow are sort of friends too. The other guppies (2 left, one got stuck in a hole in the driftwood and I found it dead ) seem fine.
Also, what is the deal with the shrimp dying?? I really want them but it seems impossible. I'm considering setting up a separate tank for them but I don't know if I'd be able to keep them alive then either. I tested my water and there is about 0-25 ppm ammonia, 0 nitrite, ~0 nitrate, 8.2 pH and the temp is at about 75 (what temp should I have it at? for all the fish, not the shrimp). I have one live plant, driftwood, moss, and some other decorations in there. And black gravel.

Sorry this is so long, I guess my main questions are:
1) What should I do about the aggressive molly and rainbowfish?
2) Why do my shrimp keep dying?
3) What temp should the tank be at?
4) Any other advice would be greatly appreciated, I'm pretty new to this

 

[nanoMama86]

Well, my dear, you need a water change, to start. The rainbowfish is probably the guppy biter, and it probably chased the guppy into the hole where it got stuck and died. 0-25ppm of ammonia is toxic and is partly why your shrimp are dying so fast. Also, with a ph of 8.2, a lot of shrimp are going to need an extended acclimation period when you introduce them. So, go do a 60% water change, seriously consider rehoming the rainbow, and give your shrimp longer to adapt before releasing them.

 

[charlotte!]

If I do a 60% will it affect the cycled water? someone told me to only do 25% so it wont start over (or something like that, I'm not too sure). And yeah that's what I was thinking about the guppy that died. I feel really bad, I didn't even consider that being a problem. Should I be worried about the holes or will it not be a problem if nothings chasing them? I can probably just take the rainbow back.
Should I be worried about the pH even for the fish? I don't even know how to lower it- I read driftwood helps but I have a huge piece in there right now and it doesn't seem like it helped much.

 

[nanoMama86]

No the big water change will not affect your cycle because your bacteria lives in your filter. As long as when you add your fresh water it is temp matched and dechlorinated you will be fine. That's why you NEVER clean your filter pads in tap water, only old tank water. It is never a good idea to mess with ph, especially for a newbie. Trust me, I have wiped out a whole tank before. A stable, constant ph is ALWAYS better than the "perfect" ph in a book. You have a high ph, ok. Choose fish that like high ph. Cherry shrimp can handle 8.2 no prob. But we HAVE to get your ammonia and nitrite down to absolute zero. And the only way to do that is a big, big water change.

 

[Dieses Madchen]

+1 on longer acclimation periods. Definitely do not mess with your pH. I am with nano on that one as i also made the mistake and almost killed all of my fish (I save half, but their lives were shorten and the rest died within 6 months of the incident) Just keep up with your water changes and monitor the ammonia. If it spikes, do a water change asap. Also, have your tested your tap water for ammonia? If you tank is cycled, then you shouldn't really have an ammonia spike. I only ask because my water has ammonia in it, so I have to use a water conditioner with ammonia neutralizers in it, just so the water is safe after water changes. Keeps the ammonia less toxic while the filter devours it.

 

[charlotte!]

Alright, water change is done. I'm not sure why I had ammonia if the tanks cycled- now I'm kind of worried Maybe I didn't do a big enough water change after it finished cycling. I'm pretty sure my water doesn't have ammonia but I'll test it. Right now the tanks down to 0 though.
Do the fish I listed do alright in high ph? I'm definitely not going to mess with it now! sorry that happened to you guys.
I put a divider up in the tank and am going to put the guppies in another tank. I feel bad getting rid of the rainbow now, I kinda like him but we'll see how he does. I keep reading they do best schooling and I'm not sure how much I want more than one of those.

 

[charlotte!]

My water does have ammonia whats the best product to use? and i left my tank a week with nothing to feed the bacteria so its not cycled anymore definitely will be waiting a while for the shrimp, maybe theyll do better once its actually cycled

 

[the_lock_man]

My water does have ammonia whats the best product to use? and i left my tank a week with nothing to feed the bacteria so its not cycled anymore definitely will be waiting a while for the shrimp, maybe theyll do better once its actually cycled

Seachem Prime - see your other thread.