Here's a link to my homemade SWP.

The wick is corrugated drain pipe with about fifty 1/4" holes drilled to perforate it.  Weed block over the bottem held with a zip tie.  Water fill pipe is 1" PVC.  Airation holes are 1/4".  Overflow hole and holes for the water level gauge is 7/16" (i think).  It's a very tight fit for the tubing, so it doesn't leak.

It doesn't seem to wick all the way to the top, though. Only about half way.  If I don't do a little water from the top, the leaves begin to yellow and look dry.  The water level in the reservoir doesn't seems to drop much from day to day.

I added more drainage holes to the wick, but it didn't improve.  Maybe the soil is too heavy?  The guy at a local soil place convinced me that Rose Soil mix would be good, but I think it's too heavy.  I mixed it 50/50 with Perlite.

Anyway, The next one I made has 2 wicks, but haven't tried it yet. And I'm going to use regular potting soil/Perlite from Lowes.

Thanks for the info James.  I want to eventually use SWCs myself.  I'll be keeping an eye out for any progress you make.  I have a bunch of 5 gallon buckets on hand...just have to wait for the trees to grow some more.

I'll take a picture of that one with a tree in it (Marylane Seedless).  And some pics of the one with 2 wick containers at the bottom.

Overall, these were pretty cheap to make.  The buckets were free (dumpster diving). 10ft 1" PVC, about $2.17.  Package of zip ties were a few dollars. Maybe about .20 cents each.  Weed block I've had for along time.  Plastic tubing was about .38 cents per ft.  I only use about 4-5" per planter.  I bought a gallon of mis-tinted pale green paint at Lowes for $12 (normally $33), plus got a $5 mail in rebate.  So I paint the buckets.  That gallon will probably paint a hundred planters.

Strong work.  I hope they do well for you.  Maybe you need a cloth wick to pull the water up higher?  Once the plant's roots get down into the wicked water you should get the benefits of the SWC.

BTW, why is the weed block at the bottom of the pipe?

So if i have to take the top bucket out for some reason, the dirt in the wick doesn't fall out. lol..

hmm.. i wonder if i can thread a few thin strips of a microfiber towel down into the wick..

I'm with you James.  I made a SWC and it isn't working the greatest in my opinion.  I've seen some references to using 70% spaghnum moss / 30% perlite to get good wicking.  The site link below mentions BACCTO Professional Planting mix for their SWC.

http://greenroofgrowers.blogspot.com/2008/07/how-make-two-bucket-sub-irrigated.html

My mix was 6/3/3 parts of spaghnum moss / coir / coarse perlite.  I'm going to guess I have the same problem you do, only getting partial wicking.  When I have some spare time I need to autopsy my SWC and see what's going on in there.  ascpete thought that maybe my tree went in to the SWC rootbound and that might be an issue too.....something to check on during the autopsy.

Keep us updated.  I'll post my findings when I remove my Hunt from the SWC.