Instruction: Generate an answer to the question by utilizing the information contained in the document.

Input:
Question: Should I get a coffee grinder to use this product?  Or would already ground coffee work just fine?
Document: I love the taste of this cold brewed coffee! I would highly recommend this product to coffee lovers... Very low acid taste, no upset stomach.
I brewed the first batch using a coarse ground coffee. Tasted the results full strength, OK. Diluted it one to one for a cuppa. Weak, hardly any flavor. Made up an iced coffee, Tasted great. Made up a second batch using fine/drip grounds, sample tasted OK. Iced coffee tasted great.Conclusion: great for iced coffee, Ok for undiluted hot coffee, not so much as a concentrate.
I really enjoy this for making a moderate amount of cold brew. I believe the large infuser helps get the most out of your coffee grounds and/or tea leaves. In fact, it works well enough to brew once again on top of used grounds and still get a strong-enough, drinkable brew. Excellent value for the money as well.
I would recommend this for an iced coffee brewer but have some reservations as a concentrate brewer. If you can reserve this for the full strength brewer I could recommend this.
This makes great iced coffee with little effort and mess. It's not quite as strong as traditional cold brew but delicious and very easy to make. If you want a concentrated syrup you'd need to brew for at least 24 hours.Overall a great product and I highly recommend.
I am really enjoying this Coffee maker and the coffee is very good. I fill it about 3/4 with normal grounds, fill it will water flip it end for end a few time and stick it in the frig for about a day. Then mix it with about half water and enjoy.The only problem I have is it would be nice if you could fill the container with water through the filter with the grounds.
I believe this is the easiest to use of all cold brewers. Takes up minimal space too. Makes smooth, great tasting coffee concentrate without a messy, multistep process. Highly recommend!
Easier to use than my old faithful toddy maker and quite the space saver! If you want stronger coffee just let it sit longer. I love that it is less acid than brewed coffee. The perfect summer brew!! !
I you like cold brew coffee, this is a easy unit to use and provides good tasting coffee. I have another unit to make cold brew coffee, the Toddy Cold Brew Coffee Maker, and it also makes good coffee, but it has some drawbacks that the Takeya doesn't have.
The idea of the system was appealing to me for coffee. I love the flavor of strong coffee but have found that brewed coffee is sometimes too acidic for me. This was not the answer for me. But I switched & now use it for loose hibiscus tea leaves & it works great! I really like the clear plastic pitcher, ergonomic handle & the design of the screw on lid/mesh basket.
Answer: You should use only course ground coffee.   Either buy a grinder and do it yourself or buy beans at a coffee shop and gave them ground for you.