Looking at the list of money market ETFs in Canada, there are not many available.
Horizons Medical Marijuana just came out on April 4, 2017. Therefore, there is not enough information available. Horizons Medical Marijuana is not a money market ETF, so it can be ignored.
Money market ETFs hold debt securities that mature in less than a year and are the most liquid, easy to sell, of all securities. Money markets also have very minimal volatility. Therefore, the coupon, interest rate, is minimal.
If we take a look a the Purpose High Interest Savings ETF, it invests money in several financial institutions savings accounts. Therefore, this is an ETF that can be used to park your money in uncertain times.