Advice On Transitioning My Tank

[the_faze]

Hi,
 
As the title says I am looking for advice on transitioning my tank.
 
Currently I have a 25G tank with 1 platy and lots of java fern.  This tank has been setup and going for the past 6 years and originally had about 5 platys and 5 neon tetras.  Nothing too crazy but it looked nice.  Especially with the java ferns.
 
Over the past 6 years I have slowly lost fish I'm assuming to age, since they always were healthy one day and gone the next. 
 
Okay so now to the actual point where I need some advice.
 
SImply put, I want to clean the tank and transition it to a new stocking.  
 
The current tank walls currently have lots of algae, and does not have a deep enough substrate (1 inch of sand) for any rooted plants.  I do not know how to do it while I still have the platy and I want to avoid a cycle. But I am mostly worried about the platy.
 
I want to restock the tank with a gourami, some rasbora's or tetras  and maybe two or three cory's.  I am also playing with the idea of putting some dwarf cichlid's instead.  I also wanted to put some plants like swords etc.  
 
Let me know if the stocking makes sense or if there are other stocking ideas I can play with.
 
 
Thanks for your advice in advance.
 
Edit in green.

 

[BerryAttack]

a few days before hand or a week, really up to you change the filter (if you have a hang on filter) so that the bacteria etc etc can grow and be all nice when you set up the tank.
okay, so what you can do is get a large bucket, and fill it up, put the platy there (no need to worry about it now its out of the way) 
you can empty the tank (save the water because you'll need it later)
then leaving about an inch to two inches of water left you can get a scrubber and scrub the walls of the tank, and clean the sand. use no soap or anything like that and rinse with the aquarium water in the buckets that you have put it in.
after set the tank up. because of all the bucket have cooled off evenly you should not need to worry about shocking the platy with the water temp difference. 
you will then need to add fresh water (water change happening now because you have used aquarium water to clean walls and sand)
you now can position everything before adding the platy in. just raise the temp of the tank slowly throughout the next few days and boom all good to go.
 
for the fish stocking now, tetras and rasbora's you can add in i would say about 4 minimum. just choose one breed.
with the cories they like to be in shoals, so about 3-4 minimum. i would recommend getting a small breed because if you are still using your 20 gallon, you don't want them to get too large.
what type of gourami are you think? dwarf? i would recommend a dwarf gourami - powder blue is very nice.
for the cichlids, go for rams, but i would hold off on this idea of getting them for awhile. you have to do research on what type of breeds you want because some are aggressive and other are not but get large. really depends on what you're looking at.
 
so in the tank it would be 
4 rasbora or tetra (pick one breed though)
3-4 cories (small breed)
1 platy
1 dwarf gourami
 
make sure you do not add more then 6 at a time for about 2 weeks. if you add too many at a time it'll kill the fish and its not good. so get the rasbora or tetra first, then 2 weeks later the gourami and or cories.
 
before adding any fish besides your platy, get your plants set up. i would say you'll need about 3-4 inches of sand. you can get play sand at a hardware store, but do a little research because some have fillers that you don't want. then rinse the crap out of it.. and when you think you are done do it again another 20 times.
 
now with plants what type of lighting do you have, or what you want. if you have the java fern then most likely low light. the higher or stronger the light you have then the more nutrients your plants need, and the higher the possibility that you'll have an algae issue. you can get a lot of low light plants that are beautiful. 

 

[the_faze]

Wow, thanks for the detailed reply.
 
I'll give your suggestion a try probably in  a few weeks, after letting the filter re-establish itself.  I'm using a hang off the back with a bio-wheel, which really seems to work well.
 
Yes I was thinking of a dwarf gourami, sorry for not specifying.  I saw a nice blue one in the pet store when I was there.  I was tempted on getting him but decided to plan things out first.  I also, saw some interesting striped ones when I did a search online.
 
I am sorry I wasn't clear, it was either the stocking I suggested or getting the cichlid's.  I don't think my tank can handle both as it will be too many fish.
 
Okay so I will need at least 3 inches of sand.  And yeah cleaning it was a pain which is why I only have 1 inch at the moment .
 
Currently I have low light but can easily ramp up the light as my hood can take two CFL bulbs.  You mention there are some nice low light aquarium plants?  do you have any suggestions that are also low maintenance.  
 
Thanks