Instagram is growing faster than Facebook or Twitter, and its engagement rates with content are far higher. But packaged-goods brands without obvious visual punch – like toothpaste or skincare products – remain largely invisible there.

Now Tom's of Maine, a natural-products brand owned by Colgate-Palmolive Co., is looking to make a visual splash without resorting to such steps as $15,000 payments to Instagram mega-influencers to post photos for their millions of followers.

Working with Mavrck (pronounced Maverick), a social-influence analytics and marketing platform that's launching an Influencer Activation Engine, Tom's this month has turned to what Mavrck CEO and Co-Founder Lyle Stevens calls "micro-influencers."

These are Instagram users "who have maybe 1,000 to 5,000 followers but engage a very high percentage of them around a very specific topic," Mr. Stevens said. "In the case of Tom's of Maine – earth-friendly products."

Mavrck has an algorithm developed by studying its own "curated" group of Instagram influencers that assigns higher rank to users with greater engagement rates on their posts – so a 1,000-follower user who averages 100 shares would rank higher than a 5,000-follower user with the same number, Mr. Stevens said.

Tom's has been on Instagram for some time, but has just started to focus more on the social network, said Bridget Burns, the brand's social media strategist. "We did a study with our target consumer and found out not only is she active on Instagram daily, but she does interact with brands on Instagram as well."

Instagram is "definitely a good place for us to be, because we don't have to worry about newsfeed algorithms preventing users from seeing our content," she said. "But it's important that the content we put out there is right for the platform, which tends to be obviously very visual."

What seems to work so far are posts of products being used (selfies of people brushing their teeth with Tom's for example) and photos of Tom's employees taking advantage of a benefit that gives them 5% of their paid time to use volunteering for community organizations.

"Some glossy ad lob is not going to play out well for us on Instagram," Ms. Burns said. "We also realized user-generated content is a great way for us to have a presence, and that's one thing Mavrck is helping us unlock."

So far, Tom's has built its community of Instagram users about 8% in two weeks to 1,000, with a goal of doubling the number this year, Ms. Burns said. Engagement rates have also been stronger than on Facebook and Twitter, she said.

The reward even for smaller brands with smallish followings on Instagram is potentially huge. The network has more than 300 million members who share more than 70 million photos daily. A Forrester study last year found Instagram delivers more than 58 times as much engagement per follower than Facebook and 120 times more per follower than Twitter.

A Shareablee study from the first quarter found Instagram accounted for 1.9 million engagement actions (likes, shares, comments, etc.) per brand among the 100,000 tracked in the U.S. -- more than double the total number for Facebook and Twitter combined.

Tom's has found some past influencer programs tended to be "one offs" where the activity didn't last long after the initial blast, Ms. Burns said. It's had better results cultivating a "Goodness Circle" of bloggers last year, and hopes for similar lasting results from its broader community of Instagram users.

Those users are compensated (and using such disclosures as #ad), but Ms. Burns said the brand is trying to make earning rewards more like "surprise-and-delight fashion, so it's not transactional where you share a photo of yourself brushing your teeth on Instagram and we give you a coupon code."

Basically, members of the Tom's Instagram community "unlock rewards" over time as they complete a variety of actions, such as sharing brand photos, with the plan being to tailor the rewards to groups of users – such as new moms – as the community grows.

Coupon codes are one way Mavrck looks to track how well Instagram programs produce actual sales online and off, Mr. Stevens said, something it encourages brands to use. While Ms. Burns said Tom's isn't doing that yet, she expects it will look to measure sales results from the effort ultimately.