ScubaPro MK20/S550 vs Hog D1

[chrpai]

This isn't your typical SB vs Hog thread.... (I own both now)

I dive a Hog D1 single tank rig. I recently put a pony tank together and went with a used MK20/S550 where the 20 has been upgraded to a 25 but the 550 was not upgraded. I paid $150 for the reg plus another $100 for a Zeagle SPG with 6" HP hose.

I bought it locally cause I wanted to have my kit ready by some diving I'll be doing this weekend. I haven't dove this new regulator yet but I'm assuming it'll be very nice.

So I'm wondering, what would the second stage go for if I sold it? Would it make sense to go with a Hog second stage ( fully adjustable, all metal barrel, standardization of regs... ) Would it make sense to sell the 1st and 2nd and go with another Hog D1 rig?

Or maybe I convert the S550 to fully adjustable (not sure what that would cost).

 

[elan]

I would not go for a diaphragm reg for the pony unless you keep it pressurized all the time.

 

[Fishpie]

I've never had a problem with flooded diaphragms vs flooded pistons.......at least once a week I demonstrate to students what to do if they leave off the rinse cap to a 1st stage by dropping a set of Conshelfs into the deep end of a pool.....still working like a champ after 2 years of this abuse without any service or maintenance.

....I have sets for just pool use that I deliberately do not service with the hope that I can show students what a reg that needs service looks and sounds like.....my OW sets get serviced normally.

chrpai....your MK20/25 is probably worth a bit more than the 550. I'd guess an eBay price of $70 to $80 for the 550.

 

[elan]

Its up to the user to decide whether they care for their regs or not and how often and when to service it. The reg will still work but it can have all that dirt inside from the water intrusion, salt crystals etc. Im not going there.

If you service a diaphragm reg after the flood in many cases you must not reuse the diaphragm as it will have imprints of the clamping rings and will not seal properly. So you have to use a new diaphragm. With a piston reg especially mk20 that has a dull piston edge you can reuse everything after reassembly so you do not need a new kit everytime.

I know some guy were running vinegar through an mk20 reg after flooding it then cleaning with the water and drying it out with air. Flow through pistons have no dead spaces where the air is not moving unlike diaphragms and flow by pistons where balancing chamber and piston head have spaces where the air does not move.

Me and my friend had 2 cases of a diaphrarm reg flood (mk17 and flathead vi) both were less than pretty inside (dirt, salt crystals). Your pool example is far from real life situation if its a chlorine pool as it is fairly clean. If it was a salt water pool the reg woul be all full of salt in a while and for some regs that do not have replacable set like most apekses it would mean a trashed reg body.

 

[Fishpie]

All good.....I thought we were heading into blown diaphragm and extruded balance chamber territory.....

Suffice to say, if either type of 1st stage gets flooded a disassembly, clean and rebuild would be necessary as a minimum.

 

[elan]

All good.....I thought we were heading into blown diaphragm and extruded balance chamber territory.....

Suffice to if either type of 1st stage gets flooded a disassembly, clean and rebuild would be necessary as a minimum.

Agreed And in case the OP cannot do it themselves there i no difference between the two as the shop will charge for the kit anyways

 

[chrpai]

chrpai....your MK20/25 is probably worth a bit more than the 550. I'd guess an eBay price of $70 to $80 for the 550.

Piston vs Diaphragms aside, you've picked up on my actual question. Let's say I could get $75 for the 550 on eBay and pick up a Hog D1 Second for $110. Should I do it? Is it enough of an upgrade to justify $35? What would it likely cost to just convert the 550 to a 600?

Or would I just be taking away value from the MK20/25 / 550 pair if I ever decided to sell the reg as a set?

 

[Fishpie]

If there are any Black Friday deals going round I expect the D1 would cost about the same as you could sell the 550 for.
I'd guess if you have a shop install a knob on your 550 you're looking at at least $20 (probably quite a bit more).
As for ease of servicing by keeping all one brand...it helps.

If you gotta have a cracking pressure knob I'd go the whole HOG and get both stages.....if not keep the SP.

 

[cbrich]

I would not even worry about the adjustment knob on the S550. But if want to sell it, I would buy from you for $75.

 

[50Fathom]

I was just at a Scubapro repair clinic to renew my cert, and during the course, the adjustable vs. non-adjustable thing got brought up, (G200B vs G250, S555 vs. S600, C200 vs. C300 etc.)

Anyhow, I asked that VERY question, since I have an S555 I was considering upgrading to an S600, and the long and short is, it's really not worth the trouble/time/expense. A well-tuned balanced non-adjustable will breathe just fine and require no fiddling on the user's part.

The adjustable regs are designed/intended to run with the knob all the way out, (easiest cracking effort), with the knob only turned in when needed, IE, swimming into a strong current or scootering, which can put a little excess pressure on the main diaphragm, causing slight bubbling/leaking. When conditions return to "normal", back the knob out and go on as usual.

It was also mentioned that the non-adjustable regs sell more in Europe, (Cayman/S555, C200, etc), versus the adjustable regs, which sell more in the US. Scubapro's marketing folks scratch their heads and just assume that, quote; "Americans just love knobs."

I could put a well-tuned S555 in your mouth and an S600 while you are blindfolded and you couldn't tell them apart.

Hell, I'm considering going to a non-adjustable second-stage as my bungeed backup because right now I'm using a G250 and I need to keep the knob turned in pretty far to prevent freeflows. And when I DO go to my backup, it's going to be either a drill or (so far not yet), a real, no-BS OOG, and I'm not gonna be thinking of tuning my reg for a fractionally easier breathing effort. It just seems kinda pointless on a backup reg.

For stages/deco bottles, I can SORTA see it, where you crank the knob all the way down, so you don't lose pressurization, then after the gas switch, you can open it back up and enjoy nice breathing. But as a pony, which by it's nature is an emergency tank, I would imagine that would be unnecessary, since if you're on it, you got bigger things to worry about.

I love my G250s and the S600 is a sweet reg, but honestly, I won't throw rocks at a well-tuned S555 or G200B.