Tom, I think you'll be pleasently suprised at how easily the fix can be made You've got all the room you need to make the change-out! I can't tell from the pics if it's 1.5" or 2" pipe, just be sure to get the same sized pipe and fittings.
Things you'll need:
~ 2' pipe SCH 40
1- 90 elbow (sch 40 socket X socket - pipe will be glued into the 90)
1- Union (sch 40, pipe will glue into the ends, be sure to take care of the o-ring, lube it whenever you take the union apart with silicone or teflon based lube and don't let it get lost!!)
1- coupling (sch 40)
PVC glue and primer
Hacksaw with good blade
Tape measure
Pencil
Rag
OK, materials procured, we're set to do this. What we're going to do is cut out the offending, threaded fittings and replace them with a glued one (there is no reason for a threaded connection there - as it's glued into imobile pipes, you can't tighten it nor unthread it to fix the leak, we take the risk of the threads leaking again away). Starting on the horizontal pipe, cut the pipe~ 3" back from the fitting, try to keep the cuts perpendicular to the pipe - anything over 1/8" out of perpendicular should be recut so that you have a good straight cut (if you want to cheat, you can measure off of the fitting and make a few pencil marks on the pipe so that you have a guide for your cut). Next cut the vertical pipe the same way. Use the rag to rub off the burrs from the cut ends.
Bad part is out - now we'll install the new piece. Following the instructions on the glue can - glue the coupling to the vertical pipe and the union to the hoizontal pipe(wipe any drips or excess glue off with the rag - let's keep this looking professional ). Dry fit (push it into it without glue) a piece of pipe into the union (the length of the pipe isn't crucial, but it needs to be long enough to dry fit the 90 onto the other end and be over the coupling on the vertical pipe- measure between the open end of the 90 and the coupling and add the extra for the depth of the fitting sockets (usually 2.5" - but double check that your fittings have a 1.25" socket). Cut a piece of pipe that size and glue it into the coupling. Now dry fit the 90 on the top of the new piece and measure between the open union end and the open 90 end, add the 2.5" and cut the final piece of pipe. Glue the last piece into the 90, now take the union apart and glue the piece with the 90 on it into the 1/2 union. Final step is to glue the 90 onto the vertical pipe - once it's on, reconnect the union. Let the glue set for the specified amount of time and you're ready to start up the pump again, with no leaks!
The whole reason for the union is to enable you to be able to get the last connection on the 90 - it's going to be the most expensive part to buy, but is a real life saver - it also allows you to 'tinker' with the filter end of the pipe without having to cut the pipe again. I'd imagine that this will cost < $30 for materials and take < 45 min. Please post any questions about anything I've been unclear on and I'd love to hear the final result!! . Good luck with this and if I can be of more service, never hesitate to ask! - Ted