problems establishing fish tank

Question
i started my tank in april.  i have a 6.5 gal. acrylic tank with several fabric plants, a 'treasure box' decoration and a bridge kind of thing.  i started with a goldfish, which died.  a tropical fish store was recommended to me and they were helping get started.  before we added 4 danios (sp?) and 2 aquatic frogs, they had me fill the tank, add cycle & stress coat, then wait a couple of days.  after adding the fish, i was going in weekly for water checks.  after 3 weeks (i think), when my water was tested, the levels were WAY off.  after chatting about what i was doing, the store thought that maybe it was because i was feeding both frog pellets & blood warms at the same time.  i bought 'cycle' which i added every day, probably for 3 weeks before the water tested allright.  they also said not to clean the tank.  after the water test was good, i added 2 snails.  after 2 weeks, 1 snail died.  had the water tested again - everything was good, but the ph was high.  all of the decorations had bushy algae growing on it, so i took them out and rubbed them down with baking soda in the old tank water and changed 1/3 of the water. it's been just over a week -- i had the water tested yesterday and EVERYTHING is off again . . . very high ammonia.  the other snail has not been active so i returned it to the store (hoping not to kill it also).  i am using cycle again everyday.  took out all the decorations.  the fish store guy had no idea what could be happening and didn't really have any suggestions.

do you??
THANX!!!  akemi

Answer
well i am not familar with haveing smails and frogs in the tank. but i have never heard of scrubbing the plants with bakeing soda! where did u here that from? I have a feeling that set every thing off. i think the best thing to do would be to put the fish in a seperate tank, change 2/3 of the water. start the pump for a while before putting the fish back in. do u use regular tap water to put in their tank? When i put more water in my fish tanks i use tap water but i use Prime to decloronate it.
corinna