Scubapro MK25/S600..thoughts
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halocline
Contributor
Very highly regarded; there are literally hundreds of threads discussing different SP models, so if you do a search you'll have lots of reading.
Love mine. Got a little more than 200 dives with it now, and it's great.
Ditto, my MK25/S600 is a little over a year old with about 100 dives on it. I have owned/dived many regs over the years and this is my favorite to date. It breathes easy and dry in any position.
realdiver7
Contributor
Great reg set! If you dive cold water, or if you like a sealed diaphragm first stage, then you can get the MK17/S600. The MK25 and the MK17 are both top-of-the-line. I have owned both, and still own the MK17.
Unless you like the swivel port turret and/or if you dive cold water go with the Mk 17 instead of the Mk 25. YOu will not notice any difference in performance between the two first stages. The Mk 25 has a higher flow rate, but it is overkill and the 177 SCFM flow rate of the Mk 17 is more than enough for any rec or tech situation.
The Mk 17 is packaged with the X650 second stage but for the same money you can get an S600 second stage with it - the dealer just has to order it that way from SP - a process that takes about a week until the reg arrives at the shop.
Either way, a Mk 17 combo is much cheaper than a Mk 25 combo with the same second stage. Of course the dealer's profit margin and the gross sales figures are also lower on the Mk 17, so they tend to push the Mk 25.
The Mk 17 is packaged with the X650 second stage but for the same money you can get an S600 second stage with it - the dealer just has to order it that way from SP - a process that takes about a week until the reg arrives at the shop.
Either way, a Mk 17 combo is much cheaper than a Mk 25 combo with the same second stage. Of course the dealer's profit margin and the gross sales figures are also lower on the Mk 17, so they tend to push the Mk 25.
Packhorse
Contributor
I have double mk25s and S600s. No complaints at all
DA Aquamaster:
Dont mean to hijack this thread but are there any tables or listings of flow rates for the 1st stages from the major brands????? My LDS used the flow rates of both MK25 and MK17 as a selling point but didnt seem to know the rates for any of the other brands that he carries....just curious if SP are the only ones that use this to market their regs??
cheers
Jeelan
Published flow rates used to be more common than they are now. As far as I know SP is the only company that currently uses them.
A large part of the issue may be that the Mk 25 with it's 300 SCFM flow rate (only from the port on the top of the turret, the other ones will top out at about 270 SCFM) makes the rest of the world look bad - including the Mk 17.
What you dealer is not telling you is that:
1. Most valves won't flow 300 SCFM of gas, so whether the first stage will do it or not is usually irrellevent.
2. Even with a valve with suitably large passages, the 300 SCFM flow rate advertised only occurs with a port plug removed with no hose or second stage installed. The smaller orifice size created by an installed low pressure hose will greatly reduce the flow and an attached second stage will further reduce the flow rate.
3. The flow rates on the highest flowing second stage available anywhere won't exceed 70 SCFM in a full out freeflow. So if you had two ultra high performance second stages fully freeflowing, you would still not over breathe a regulator with a "only" a 150 SCFM flow rate.
4. Consequently, anything over 150 SCFM is in excess of what you would need for any technical or recreational diving purpose where the worst case scenario would be two extremely heavy breathing divers breathing off one first stage regulator at depth.
5. You could theoretically support four ultra high performance second stages with a Mk 25, but the high flow rate would cause the first stage to freeze up even in tropical water. And unless your configuration includes 4 ultra high performance second stages on one regulator, you will never come close to using 300 SCFM of gas.
6. In the event you had some sort of catastrophic breakage, (like snapping the LP port turret off) the only "advantage" the MK 25 will offer (assuming the tank valve can accommodate the high flow rate) is dumping the contents of your tank(s) twice as fast and/or dumping twice as much gas in the time it takes to close the correct valve as it would with the Mk 17.
So in short, when you look at it from a system perspective, the Mk 25's 300 SCFM flow rate is pointless - for everything other than marketing it to divers who aren't aware they don't really need that much flow rate and in fact probably don't actually want that much flow rate.
This does not mean a dealer is intentionally misleading you however, as most dealers have just not done the math or thought it through. They have just made the mistake of beliving SP's own marketing hype. And 25-30 years ago, flow rate was a serious issue as many regs did not offer even a 100 SCFM flow rate and could in fact be overbreathed under very demanding conditions at depth (a situation that is still true today in lower performance first stages like the Scubapro Mk 2 Plus, Aqualung Calypso, etc)
Response rate is at least equally important as a first stage that is slow to initiate flow will result in an excessively high drop in intermediate pressure. I have bench tested the MK 17 and Mk 25 side by side as well as conducted subjective tests with one on each post at 150 ft. With identical second stages attached, there is no noticeable difference on the bench or in the water in terms of inhalation resistance, gas delivery or IP drop between the Mk 17 or Mk 25.
In my opinion, the Mk 17 is an excellent first stage that is much better suited to a much wider range of conditions than the Mk 25 and it also happens to be a much better buy as SP has not yet read the writing on the wall (and is still stuck on the 300 SCFM flow rate myth) and moved it to the to of the heap as it's premier first stage.
The darker side is that sometimes dealer motivtion can be involved in the sales pitch for a Mk 25 as the Mk 25 has a better profit margin than the Mk 17 and since it costs more, it also helps bulk up their gross sales. This is important to a dealer as once certain sales levels are reached each year, SP dealers receive a reduction in their dealer cost for items - which then further boosts their profit margins. So it is usually advantageous to a dealer to upsell the customer to the Mk 25.
A large part of the issue may be that the Mk 25 with it's 300 SCFM flow rate (only from the port on the top of the turret, the other ones will top out at about 270 SCFM) makes the rest of the world look bad - including the Mk 17.
What you dealer is not telling you is that:
1. Most valves won't flow 300 SCFM of gas, so whether the first stage will do it or not is usually irrellevent.
2. Even with a valve with suitably large passages, the 300 SCFM flow rate advertised only occurs with a port plug removed with no hose or second stage installed. The smaller orifice size created by an installed low pressure hose will greatly reduce the flow and an attached second stage will further reduce the flow rate.
3. The flow rates on the highest flowing second stage available anywhere won't exceed 70 SCFM in a full out freeflow. So if you had two ultra high performance second stages fully freeflowing, you would still not over breathe a regulator with a "only" a 150 SCFM flow rate.
4. Consequently, anything over 150 SCFM is in excess of what you would need for any technical or recreational diving purpose where the worst case scenario would be two extremely heavy breathing divers breathing off one first stage regulator at depth.
5. You could theoretically support four ultra high performance second stages with a Mk 25, but the high flow rate would cause the first stage to freeze up even in tropical water. And unless your configuration includes 4 ultra high performance second stages on one regulator, you will never come close to using 300 SCFM of gas.
6. In the event you had some sort of catastrophic breakage, (like snapping the LP port turret off) the only "advantage" the MK 25 will offer (assuming the tank valve can accommodate the high flow rate) is dumping the contents of your tank(s) twice as fast and/or dumping twice as much gas in the time it takes to close the correct valve as it would with the Mk 17.
So in short, when you look at it from a system perspective, the Mk 25's 300 SCFM flow rate is pointless - for everything other than marketing it to divers who aren't aware they don't really need that much flow rate and in fact probably don't actually want that much flow rate.
This does not mean a dealer is intentionally misleading you however, as most dealers have just not done the math or thought it through. They have just made the mistake of beliving SP's own marketing hype. And 25-30 years ago, flow rate was a serious issue as many regs did not offer even a 100 SCFM flow rate and could in fact be overbreathed under very demanding conditions at depth (a situation that is still true today in lower performance first stages like the Scubapro Mk 2 Plus, Aqualung Calypso, etc)
Response rate is at least equally important as a first stage that is slow to initiate flow will result in an excessively high drop in intermediate pressure. I have bench tested the MK 17 and Mk 25 side by side as well as conducted subjective tests with one on each post at 150 ft. With identical second stages attached, there is no noticeable difference on the bench or in the water in terms of inhalation resistance, gas delivery or IP drop between the Mk 17 or Mk 25.
In my opinion, the Mk 17 is an excellent first stage that is much better suited to a much wider range of conditions than the Mk 25 and it also happens to be a much better buy as SP has not yet read the writing on the wall (and is still stuck on the 300 SCFM flow rate myth) and moved it to the to of the heap as it's premier first stage.
The darker side is that sometimes dealer motivtion can be involved in the sales pitch for a Mk 25 as the Mk 25 has a better profit margin than the Mk 17 and since it costs more, it also helps bulk up their gross sales. This is important to a dealer as once certain sales levels are reached each year, SP dealers receive a reduction in their dealer cost for items - which then further boosts their profit margins. So it is usually advantageous to a dealer to upsell the customer to the Mk 25.
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