Molly Tank Crashing? Help!

[FallynLeigh]

Hello all.  This may or may not sound like an emergency, but I've never had this happen.
 
Heres the back story, you can skip it, but it may help determine whats wrong:
 
Okay, so I recently got 5 mollies from my LFS and they said they'd be fine in a 10 gallon.  Next day theres 30 fry, and 30 more the next day.  Then one of the original mollies die, although she was a bit deformed to start with, and my mom gets another to replace it.  The adults are eating some of the fry, but there seems to be 20-30 (I count around 35 but they move a lot, those little boogers) that are good at hiding.  Then last night ANOTHER dies.  This one seemed healthy, but when I got him out his scales were a milky white (he's originally black) and super slimy.  
 
So now the problem:
 
I tested the water and it was wayyy off the charts.  The nitrates were >200 ppm, the nitrites were 10 ppm, and the pH was 6.0.  My mom sad that adding baking soda would help the pH and possibly the nitrates/nitrites.  So she added 1 tsp of baking soda to a little bit of de-chlornated tap water and then added it to the tank.  That was at 11 pm (EDT) last night.  This morning I checked it and the nitrates are 200 ppm (went down a tiny tad), nitrites are 10 ppm, and the pH is 6.3 (went up a bit but far off from the 7.0-8.0 that mollies like).  None of the fish are showing odd behavior and the fry seem okay.  I just added 1/2 tsp of baking soda to 1 & 1/2 cup of de-chlornated tap water and then added it to the tank.
 
Tank STATS:
10 gallons
Nitrates: 200 ppm
Nitrites: 10 ppm
pH: 6.3
2 female mollies
2 male mollies
~25 fry
medium planted
 
Tap water:
Nitrates: 20 ppm
Nitrites: 0 ppm
pH: 7.0
but the general hardness is wayyy low
 
 
Any suggestions?   Please help!
 
[EDIT: I do have a 35 gallon tank on the way, because I know that the over crowding is causing at least some of my problems]

 

[Sophie]

Forget the pH for now. Messing around with that will only stress the fish more and probably finish them off.
 
What's the Ammonia reading? The Ammonia and Nitrite are the most important (if you read the article I posted to you properly).
How long has the tank been running?
Have you done any water changes yet?
 
Stop adding baking powder.
 

 nitrates are 200 ppm (went down a tiny tad)"

 
The Nitrates will not decrease unless you do a water change.

 

[the_lock_man]

It sounds as though you have the paper strip tests, which are unreliable, BUT (and I'm deliberately using block capitals) WE HAVE TO ASSUME THAT YOU HAVE A LARGE AMOUNT OF NITRITE IN THE TANK.
 
Nitrite is highly toxic. It attaches itself to the haemoglobin in the fish's blood, and prevents it from transporting oxygen. Assuming that the strip test is relatively accurate, that is enough to kill the fish very quickly.
 
If you have any, ADD 4g OF AQUARIUM SALT NOW. Salt will also enter the fish's blood stream through the same parts of the gills that nitrite does, and at a concentration of 10x the nitrite concentration, it will stop the nitrite from doing so, thus allowing oxygen to attach to the haemoglobin.
 
THEN DO ENOUGH MASSIVE WATER CHANGES TO BRING THE NITRITE LEVEL DOWN TO 0PPM. THIS MAY TAKE SOME TIME, BUT IS NECESSARY TO PREVENT FURTHER FISH DEATHS.
 
Then, and only then, answer Sophie's questions.
 
Assuming I'm right about the strip tests, you also need to buy a decent liquid test kit. And then I reckon you need to learn about cycling a tank.

 

[Sophie]

That or have the tank extremely heavily planted etc

 

[fluttermoth]

Yes, your problems are caused by overcrowding.
 
You need to up your water changes. Normally I'd say start off with one large change, but your fish will be 'used to' that bad water now, so a big change could shock them too much.
 
Start by changing 20% of the water today. Do not add anything else to the water, apart from water conditioner/tap safe. Then do 30% tomorrow, 40% the day after that and so on, until the tank water is the same as the tap water.

 

[Sophie]

Was meant for the above post.
 
Dang, TLM beating me to the punch!

 

[FallynLeigh]

Okay, so I'll put 4g of aquarium salt in.  I do have the test strips.  The tank is over 5 years old and is very mature.  
 
For water changes, what type of water do I put back in?  My mom always does them....

and the test strips don't tell me what the ammonia is.  my mom probably won't agree to buying an actual test kit.

 

[the_lock_man]

Yes, your problems are caused by overcrowding.
 
You need to up your water changes. Normally I'd say start off with one large change, but your fish will be 'used to' that bad water now, so a big change could shock them too much.
 
Start by changing 20% of the water today. Do not add anything else to the water, apart from water conditioner/tap safe. Then do 30% tomorrow, 40% the day after that and so on, until the tank water is the same as the tap water.

 
I thought I'd read elsewhere that this tank is quite new. If that's right, then follow my advice regarding the water changes. Certainly the fish are recent additions.
 
I hate disagreeing with FM, but when she says do not add anything else, you are safe to add the aquarium salt as this will ease the suffocation the fish are suffering. Do not add any more baking powder, or anything else to alter the pH. This is NOT an immediate problem.

Okay, so I'll put 4g of aquarium salt in.  I do have the test strips.  The tank is over 5 years old and is very mature.  
 
For water changes, what type of water do I put back in?  My mom always does them....

and the test strips don't tell me what the ammonia is.  my mom probably won't agree to buying an actual test kit.

 
OK, follow FM's advice re the amount of water changes. Replace with fresh dechlorinated temperature-matched tap water.
 
An ammonia test is an essential test kit to own. I suggest you allow her to use your account on here to ask questions as to why I say this.
 
Was there a period when the tank was empty? I ask because you say that the 5 mollies are new - what else was in the tank prior to the introduction of the mollies?

 

[FallynLeigh]

 

 
 
OK, follow FM's advice re the amount of water changes. Replace with fresh dechlorinated temperature-matched tap water.
 
An ammonia test is an essential test kit to own. I suggest you allow her to use your account on here to ask questions as to why I say this.
 
Was there a period when the tank was empty? I ask because you say that the 5 mollies are new - what else was in the tank prior to the introduction of the mollies?
 

 
How do I de-chlornate water?  I have a 1 gallon jug with water that my mom de-chlornated but I don't know how.
I'll try to talk my mom into an ammonia test kit.
The tank was empty for about 5 days.  Prior to that it had a single angel fish in it for over 5 years and never had a problem.  There are also like 250 very large snails that have been in there for 4-5 years.  The plants, rocks, and decorations are all also 5-6 years old.

 

[Sophie]

If there was nothing in the tank before, if it was left running without anything living in there and/or it was turned off (the filter) for a long period of time it won't be classed as 'mature' anymore as the beneficial bacteria would have died off.

You dechlorinate water using a dechlorinating liquid purchased at your LFS.

 

[fluttermoth]

You should have a bottle of something called 'tap safe', water safe' or water conditioner', something like that?
 
I do agree with tlm about the salt; add that after you've done a 20 or 25% water change.

 

[Sophie]

Please thoroughly read the cycling article I linked to you
It will help you understand what we are trying to explain.

 

[FallynLeigh]

The filter was left running when there were no fish for those 5 days.  And I did read the cycling article, twice.
 
I don't think we have any water conditioner... I'm pretty sure my mom just leaves the water out for a few days.  She's had fish for 30+ years, and so I just go along with what she says.  She's in charge of keeping the tanks balanced and I do the basic care.

I have something called "ammo lock" it says:
"Instantly detoxifies ammonia
removes chlorine and chloramines
for fresh and salt water"

 

[Sophie]

API Ammo Lock?

 

[FallynLeigh]

API Ammo Lock?

 

Yeah, thats it... how should I use it?  Direct into the tank or into water for a water change or both?