[rijune]

Dear all,

I apologise if this goes against the forum rules, please delete it if so. I was unsure if it would break the 'must read rules' as it involves synthesis/preparation, but it is not a drug nor a bomb.

It has been more than a decade since chemistry class so I am writing with hopes for your help; I was not a great student either. I am trying to make a small solution involving ammonium chloride to use in my aquarium. It is often used during the initial startup of a tank to help colonise/establish nitrifying bacteria to make it safer for fish inhabitants i.e. fish cycling. It is similar to this commercial product by Dr Tim (https://www.amazon.com/dp/B078HYGK9D/ref=psdc_2975478011_t4_B001LULBXI).

The description states it is 50mg/L, which I think is 5% concentration. I would like to make a 25% solution as according to this calculator (http://spec-tanks.com/ammonia-calculator-aquariums/) it would take 48 drops (1ml=20 drops) in a 40L aquarium to achieve a 3ppm NH3 reading vs 10 drops with 25% concentration. It's also a concentration I've used in the past but have since run out but I digress.

I believe if I add 250mg to 1 litre, I can achieve 25% conc, however I do not have a scale to weigh this out, only one that reads to one decimal figure. As such, is my only option to add 1 gram of NH4Cl to 4L of water in order to achieve this?

Furthermore, can I simply add Nh4cl to h2o to dissociate to Nh3? For Cl, I believe the ions have a negligible effect on the plants in the tank as about half the g/mol of Cl, so 1ppm of Nh4 should give 2ppm of Cl. A quick search states in natural freshwater habitats, there is ~200-300ppm of Cl.

All in all, it would be nice to be able to make something that I could never run out of as opposed to purchasing, but if it is too complicated, it might be best to resort to giving money to Dr Tim.
Help much appreciated, thanks.

June   

[chenbeier]

I think there are some calculation errors.
5 % of 1 liter ~ 1 kg is roughly 50 g. Not 50 mg. Normally you need specific gravity for this. For a 25 % then 5 times 250 g.
50 mg in a liter is roughly equal 50 ppm.

[Enthalpy]

Don't try to prepare ammonium chloride at home. Apparently you don't have the skills, and it doesn't make sense for a compound that is mass-available.

Just search for a decent retailer who won't charge astronomical amounts to put "for aquariums" on the package.

It's quite possible that all quaternary ammonium salts are unavailable presently, as they serve as disinfectants.