so my names john, iv been on another forum for this but i figured, the more opinions the better. bear with me here because my "c" button does not work and i have to copy and paste to use it haha. so my story: 2 days after xmas, my girlfriend bought me a halfmoon betta from petco after me complaining for a few months how i missed having fish and suh. so, i ome home, see the fish, next day im out, buying a new 15g aquarium, a common pleco, a Chinese Algae Eater, and 2 snails, one black? and a gold inca. snails lasted 2 days, algae eater Crushed himself between some roks. so i went bak, returned him and bought a glass Cat and a few guppys. WENT TO 3 DIFFERENT PLAES TO GET THE GUPPYS. long story as far as that goes but yes 3 different plaes one being a striCtly aquarium store. the other petsmart and peto. now i did NOT CYCLE MY TANK. after goign to the other forum, and explaining my problem, is was informed about doing that. so i had to do a fish in, using tetra safestart. this was about 3 days ago now. i have been testing ammonia, nitrates, nitrites, ph, hardness, hlorine, and alk. everything has been with in needs sine iv used the tetra. before, my nitrates had been at 20ppm. now im geting a little ahead beause i did buy 2 bumble bee Cats and a marble loaCh and some neon tetras (some guppys died and i returned for tetras) yesterday my glass died and so did a few of my tetras. brought them bak, got a Clown pleCo, and 4 ghost shrimp. i ame home, did a 80% water hange beause it was really loudy. now i found my bumblee bee and a guppy both dead. and then 3 or 4 hours after the water Change, i find all 4 shrimp dead, and my Common pleCo dead. what in the hell am i doing wrong? i now have 4 guppys, one neon tetra, 1 marble loah, 1 Clown pleCo, one bumble bee Cat, so 8 fish right now. prolly going to lose a guppy and maybe even the marble by morning seeing how niehter look all too well. any ideas people? my ammonia sine the water Change is now .25ppm, my nitrates arent even showing up on my strips (but is slightly pink) no nitrites, no hlorine, 75 hardness, 40 alk, and about 6.8 -7 ph i think im going to go tomorrow to the petshop when i retrun all my deads and buy a master api test kit

First off, stop adding fish. Of any kind. Until you know what in the world the problem is, you shouldn't be adding more fish.

I think your tank is not cycled. Tetra SafeStart is a great product, but in no way is it a "dump in your tank and Presto! Cycled tank" wonder product. The cloudiness you saw was a nitrifying bacteria bloom.

My advice:
#1 stop adding fish. If you lose some, you lose some. Don't add more!
#2 test daily, and if your levels of ammonia or nitrite get over 1 ppm -2 ppm, do a 50% water change. Don't worry about cloudiness - that is beneficial bacteria trying to set up shop in your tank. ONLY do a water change if your levels of ammonia or nitrite get high, because those two are what are killing your fish.
#3 if you have test strips, get rid of them or use them up fast and invest in a better testing kit. Strips are cheap and easy, but they're not very accurate. I use the API Master Freshwater Test Kit, which is a liquid titration kit ($25-$35 from PetsMart), and it is MUCH more accurate.

If you lose ALL your fish, then start adding flake food without adding more fish, and let the food decompose and generate the ammonia you will need to get that cycle going and more established in your tank.

Sorry it has taken learning the hard way and many fish deaths, but I'm afraid many of us have fallen victim to not knowing the nitrogen cycle when we dove into this hobby. Hope you can minimize your losses from here on out.

Here's a bit of reading material on the aquarium nitrogen cycle, if you care to read a bit more. Sorry for your losses.
The Aquarium Nitrogen Cycle
Fish Poop and You: A Primer

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Officially fishless until after the move....tune in later for details!