Setting up 10g guppy x molly tank, brackish Q's article doesn't answer.

[knifegill]

I 've heard that hydrometers (the floating thermometer type) go bad after awhile. What could cause this besides mineral build-up? Mine was obtained used, so I need to know if it can be truly expired or not.
I have already added two and a half total tablespoons of marine salt to this ten gallon tank, but the hydrometer has not budged from 1.000. Can I get a ballpark on about how many tablespoons would be going into ten gallons to get it to around 1.005? I know I have to do it in gradual weekly increases. I just have no idea if my measuring tool is working or if I've not added enough salt to make a difference.

 

[knifegill]

I've come across several sites saying that a table spoon per gallon will get me to 1.005. In that case, when I do my 50% water change today, I'll need to add just over one table spoon of marine salt to my five gallon bucket to maintain current salinity. Then, during future water changes, I can gradually increase the amount until I am adding a tablespoon per gallon per each new bucket, checking it with the hydrometer, and eventually attaining the precious 1.005 salinity.
Now for the hardball question: Do Yucatan mollies really need this salinity?! Or more or less salinity?

 

[RyanP]

I think your just goin to have to experiment with it. When i mix salt, i use over a cup of salt in a 5 gallon bucket to get my mine to 1.020 in my marine

 

[knifegill]

Over a cup?! That's a lot, but your salinity is higher than I'm shooting for. It does give me a rough baseline, though. About a quarter cup per five gallons will be my eventual dose, then I'll check it with the floater to make sure I'm close. Thank you so much, RyanP.
Update on muppy/golly production:
So far so good. The big Yucatan I brought home first had a hazy eye but that went away the hour I added salt, so it looks like a little goes a long way. I think I'll probably keep it on the low side of salinity, between 1.001 and 1.005. I had to upgrade to an 18gal because I added some mollies from a lady on craigslist and the one I had decided all new fish were the devil. I never knew mollies to be aggro before! So I put her in a quart-sized critter-keeper and let it float freely in the tank for a day while I got the 18 set up. Then I moved the fish, filter and water to the new tank and let her out after the move. She doesn't seem as murderous now, but she might still be in that confused stage fish get in a new tank for their first day.
The tally is two male guppies, six female mollies. In six months, I'll know if I'm getting hybrids or not. Fish 'born' before then could easily be from previous matings, so unless they look a lot like guppies in coloration, they are food. I'll add the floating fake plants of death tomorrow. I hate them because they get so algae-ridden and trap food in them. Blech. Soon I'll have enough java moss to fill that role.

 

[festerfish]

you kind of have to set up your own systim i use about ten table spoons for a 3 g bucket for a SG 0.013 mollys are vary addaptible and can even live in full marine. they will be triggerd to bread at about SG 0.005 so the SG is totaly up to you

 

[knifegill]

Yeah. 1.005 is my target concentration, but I have to let the bb adapt/convert to saline. If I added the full dose now, I'd get an ammonia spike. Although, five of the six mollies I have came from planted amazon tanks with no salt at all and were three or four generations in fresh while actively breeding. But for the huge wild-looking yucatan-type mystery mama, I've definitely got to go for the brack.