I started a basil plant using the kratky method, which I'm growing inside under a grow light - first time trying this.

The nutrient solution I'm using is master blend 4-18-38. I'm using 2 grams per gallon of masterblend and calcium nitrate, and 1 gram of epsom salts.

Plant has been in solution for about three weeks now.

The first thing I noticed which got me concerned was one leaf had a brownish border around the leaf. I cut that leaf off.

But looking at the leaves generally, they seem a bit on the yellow side, somewhat pale.

The plant does seem to be continuing to grow slowly but surely however the coloring of the leaves doesn't look very healthy to me.

I'm guessing this might be caused by a nutrient imbalance? Or could it have another cause? Any suggestions on how to correct this would be appreciated.

That's the correct use of MasterBlend/CN/MS for one gallon. There's a lot of talk about nutrient shift but remember hydro is a natural attraction to gadget geeks who like to nitpick. Your nutrient is right, precisely what I use for Kratky, DWC, etc.

You don't give details of your lighting. Very approximately, the rule of thumb for LED is 40W per square foot. That's 40 watts true LED fixture consumption, NOT the claimed equivalent watts. Sellers make bold claims about coverage, and it's almost always exaggerated. Inadequate light can result in pale foliage and poor growth. But lights too close can burn foliage. This is another area where people get pedantic. I always did well with greens with the lights starting out about two feet above the base of the plant and staying there unless the plant grew too close to the light.

Pale foliage can also be lack of nitrogen, but you're just not going to be short of anything this early using MB. Check your pH. It depends largely on your local water that you start with. It should be about 6 or slightly lower. You can get a simple test kit or strips where aquariums are sold.

There's little to be wrong with Kratky. Get the light and pH right. Make sure that the plants have consumed enough nutrient that there is some part of the root mass in free air and the end in the nutrient. That's Kratky's great compromise, that aeration is entirely passive. You can easily convert to a Deep Water Culture operation by adding an air pump and airstone, which will provide air to roots, even if completely submerged. Kratkly is a compromise in order to work off-grid, but plants will appreciate aeration.

Since I am having a similar problem, and having read the reply, I'm guessing this photo would show me burning the leaves off of my basil? Do you concur?

On that assumption, I have already moved the light up, and the basil back a bit... the smaller plant is Ghost Pepper which seems to like the light just fine as is.