Beef heart will bulk up your tsn fast but, as stated, you should only use it in a mixed diet.
Keep it on a staple diet of sinking pellets and supplement with the beef heart, market shrimp, tilapia fillets, and blood worms. As the tsn gets bigger, you can move up in worm sizes up to night crawlers.
A varied diet is a happy healthy shovel nose.
My exact diet for my RTC, he is 8" at 10 weeks. Follow this diet and you will do well. I sometimes subsitute the market shrimp for hikurari krill