A 29 grow out won’t last long, my Flowerhorn grew 11/2 inches a month until it hit 8 inches
+1 your flowerhorn will grow out of that tank by at least 3-6 months which goes by faster than you'd think. I know from experience growing out a flowerhorn in a 29 and it's not ideal. You can keep it in there for a few months but you should be making plans and preparations for a larger tank (55/75 gallons) as soon as it is in the 29.
That should work for a Flowerhorn, but if it were me, I’d get a 75. The cost and space it takes up should be very similar to a 60
The 75 and 60 are both 4ft tanks, the 60 I believe are 12-13” wide and the 75 is 18” wide. Those 6 inches make a big difference when your Flowerhorn gets to be 10-12” long. Keep an eye out at petsmart, I picked up a 75 with light, stand and glass lids for $250 on sale
