watering with a hose will be a challenge if you're using plastic mulch. you'll have to direct the water into the planting holes at low pressure. the plastic will suppress weeds and conserve moisture. it will help with plant diseases since there won't be soil splashing up to the leaves when it rains. most plastic mulch users lay drip tape under the mulch.

Wood mulches laid on top of the soil do not tie up nitrigen except for in the thin layer of soil where the mulch touches.

Since you were gardening in containers the blame you are putting on the mulch for the poor growth could have easily been due to the nutrients in the potting mix washing out when you water. Containers need fertilized routinely for good growth. They also need watered regularly but if you water too much or if you used a poor quality mix that retains water and compacts then growth can be stunted as well. (Hopefully you didn't use actual soil in the containers.)

I would forgo the "biofilm" and use a natural mulch instead. Organic mulches break down and as they do they benefit the soil. They also keep the soil cooler and help conserve moisture. Cedar chips are but one expensive option. If you do a search on this forum you will find a multitude of different mulch options. Most of which you can get for free or acquire cheaply.

Many plant diseases are not only soilborne but also airborne. So while using a mulch to prevent splashing will help somewhat your plants may still have disease issues.

Rodney

I strongly agree with Rodney above. I'm a great fan of natural mulches, but I use whatever free materials I can scrounge, and have never bought mulch. Woods chips are waste from yard care or tree care companies, and I also use whatever stems or stuff I can glean from the rest of the garden, or from wild areas nearby.