Idexx Quanti-Tray Review

Note: This isn’t a sales pitch. This also is not sponsored by Idexx. This is an honest, end-user review.

I’m always on the prowl to find ways to make my job easier. Some may call that lazy, I call it efficient. Whether it’s a new method, process, or tool, I’ll always take the path of least resistance. And that is especially true being the plant manager, as I’m always looking for ways to save money and increase productivity. The Idexx Quanti-Tray meets all the criteria for what I am looking for in a process improvement at my facility. It only took a quick demo from Idexx for me to see the value in their equipment and method versus the tried and true membrane filtration most plants in Michigan use for wastewater treatment plants. Simply put it is faster, easier, and more accurate.

I’ve been in the industry long enough to remember when the Hach TNT methods weren’t the standard. I remember having to do the old ascorbic acid method for total phosphorous and messing it up more times than I can count. Dont lie, you know you boiled away all your sample too. Once the Hach TNT method was approved it created a much faster, easier, and in the long run, cost effective method. Nearly all the projects I’ve worked now use that method as it is so much better than old method. That is exactly how I feel about the Idexx Quanti-Tray method. It has been approved for drinking water for many years but was only recently approved for wastewater testing.

I know many plants that still run the membrane filtration method. Filter your sample through the grid filter, put it into the dish along with the media for the bacteria to grow and wait 24 hours. You can now have fun trying to count out all those blue colonies. Ideally you wouldn’t have any colonies but that doesn’t add any entertainment value to this paragraph. It isn’t the most time consuming test to run, but when you compare it to the Idexx Quanti-Tray method, it’s day and night. Simply grab your sample with the sealed, pre-sterilized bottle, add the Colilert-18 reagent and gently swirl. Once it’s mostly dissolved add that precise 100 ml sample to the Quanti-Tray and run it though the Idexx Quanti-Tray sealer and put the tray in your water bath. You can read the results in 18 hours, which is faster than the membrane filtration method. It is also easier to read, as the tray wells will turn yellow for fecal coliforms and all you have to do is count the amount of wells and cross reference it with the chart Idexx provides you to figure out your MPN. Not only do you get more accurate numbers (counting blue colonies never really seemed very accurate to me), you also do not have to run multiple dilutions as the range on this method is far higher.

Honestly, my favorite thing about the Quanti-Tray method is that I don’t have to mess with sterilizing bottles and dilution water in an autoclave. Nothing better than going to run a test and realizing you didn’t make any dilution water or sterilize the sample bottles. I definitely would never forget to do that, so I’d simply blame it on the lab tech. I am kidding. It happens and that’s why this method is just so much better in my opinion. Everything comes sterilized and ready to go out of the box. It drastically reduces operator error and increases efficiency all around, especially if you are rotating people in and out of your lab.

Another nice feature is that this method is capable of testing for both E.coli and fecal coliforms. I know a lot of states require E.coli testing for wastewater whereas Michigan is still a little odd and requires fecal coliforms for wastewater.

It’s not all sunshine and rainbows. The up front cost of the sealer is going to put you back around $5,000. You’re looking at about another $4,000 for bottles, Colilert-18 media, and trays. We were all in with a years worth or reagents for about $10,000. With the current economy that price is probably higher. This is a hefty up front cost for a lot of treatment plants but in the long run I think it is worth it. We did some rough math and the total cost for Idexx reagents only increased our lab budget by around $200. However, you are saving significant manhours by reducing the entire test to under five minutes. I’m not kidding, it literally will take you less than five minutes to run this entire test, closer to two minutes. Honestly, with the manpower savings alone it was worth the money. With all the time you’re saving you can make sure the lab is caught up on the QA/QC and control charts for the next inspection by your regulatory authority. 5/5 rating.