Jack,
Ok I'll do my best here,
First things first, make sure that you are using enough sulfur media per your system requirement and size, any brand you choose should give you a rough idea, for example I use 40 oz of carbon, 1 pound of gfi and roughly 30 oz of lsm sulfur media per month. Now you do not have to change your sulfur media of at all, 6 months give or tale just watch to see if it is breaking down. It's hard for me to be supportive of the diy chambers. Over the years I have seen many diy projects built and many fads come and go and I am of the opinion that they are more bother than they are worth. As for a media chamber for sulfur, you might find that as the media breaks down it's gets very small and can make it's way into you display tank. I had this happen on an original set up and I think it made my fish sick, but I cant say for sure. So you need to , or should, IMO pass your effluent through another medium ie aragonite, carbon, gfo etc. In your situation I would pass it through aragonite due to your high phosphate levels, this could help stabilize your ph. Remember that the effluent from the sulfur will have a slightly lower ph than your tank, thus it can bring down the systems ph over time. Back to diy, now dont get me wrong I love the idea of building things for yourself and not getting caught up in all the rage and buying up everything in sight. However I think that a good quality acrylic chamber ( mine are mrc) are well worth their money. The ones I purchased each hold around 20 oz of media and were about $150 a piece for just the reactor , no pump. It sounds like a lot but I've thrown out a lot of poly chambers over the years that just get brittle and break. As besides, if people are willing to spend 1-10k on a skimmer than what's the prob with a $150 chamber right? So back to your set up. Obviously the more media or obstruction you put into the effluent the harder it will be to get a stable siphon going. I have found I get best results by Using a pump so I can pressurize the chamber and control a slow drip rate. You can do this with your set up it will just take a bunch of fiddling around and once again I would strongly reccomend utilizing a sponge or screen and aragonite on your set up. I wouldn't have much to say about the drip rate other than fine tune it to what works best for you. I find the rate doesn't really matter as long as I can smell a little but of sulphur and there is no air bubble in the chamber. The effluent on my system runs around four drops per second and remember this is also after passing through my calc reactor. The two put together keep my kh high ( maybe too high in some people eyes like 13-16) my ph is always 8.3 Ish and my calc around 450 give or take. I should probably mention that I have a 180 g display , 20 gal sump, very small fuge like 5 gallons, uv sterilizer, one gfo reactor, one carbon reactor, nitrate reactor and calc reactor, thats it, not even s skimmer is in use. I feed heavily ie twice a day and enjoy lots of fat happy fish swimming in my reef, around 25 I think. My corals are all across the board, from a 12 inch derasa to a nearly 20 in purple gigantea to leathers to pipe organs to acros. I like a little of everything!! So this is what works for me for now. Also I am a firm
Believer that absolutely nothing take the place of water changes !! I change 30 gallons every two weeks at the latest. If I notice things seem a little weird I'll chane it more often. I do this the old fashioned way by lugging buckets up the stairs of ro water, it's a pain but a beautiful reef is well worth it! Remember in life nothing takes the place of determination and in our hobby nothing takes the place of good husbandry!
I hope I've been able to help!!
I'll do my best to answer any questions you can throw at me
