Nice job on your stand. Pine is notoriously difficult to stain evenly. It tends to get blotchy. I've tried a number of prestain treatments to try to minimize the blotchiness, but nothing works any better than a 1 pound cut of dewaxed shellac. You can buy Zinsser SealCoat at most Home Depots or Lowes and mix it 50/50 with denatured alcohol to get an approximate 1 pound cut. It is probably easiest to apply this with a brush. It will dry very fast, so don't overbrush it. After the shellac has dried for a half hour apply the stain as directed on the can. I prefer using a rag for most oil based stains.
Gel stains have a reputation for minimizing the blotchiness on some woods. I don't have much experience with them. The few times I have tried them I found them to be difficult to use. They tend to dry too fast on large projects like your stand.
Good luck with your project.
Oh, by the way, Miracles in Glass in Toronto, Canada builds very nice tanks. They just built a Starphire 120 gal. tank for me, and I am very impressed with their work. Great people to work with and reasonable prices, too, considering the quality of the finished product.