My AN/DP/Helitrox course

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I bought a roll of the fancy GUE contents stickers 5 years ago because I like the layout. Still have a lot left, the roll has way more than it looks like on it. I think they're really nice and considering how many it comes with, worth the price.

As to MOD, all my cylinders are permanently marked. This is simpler if one uses "standard" mixes. I also find it becomes more important when your diving frequently involves multiple cylinders. MOD stickers are pretty inexpensive. If I have to temporarily repurpose a cylinder for something other than its marked MOD I just put blue tape or duck tape over all the MOD markings, not just the outer one, clearly marked with a magic marker.
 
...And you don't even wanna know how many Aussie koala's it goes for.... well, in the interest of demonstrating just how fantastic of a deal the EE price is, 89 criminal pounds (no quokkas).


:D:D
 
So if you put permanent numbers MOD stickers on the side of your tanks, how do you adapt when you change the mix?
This is a valid question for your back/travel gas and your deco gas.
I was instructed to always use the best mix for your back gas, which can change on each dive. Shouldn’t you alway try for the best mix? Additionally, your deco gas should also be matched as per the dive and not pigeon yourself to only 1 mix because your tank is marked as such.

I much prefer tape on both the neck and side. I never had a tank that the sticker rubbed off in fresh or salt water. Of course you have to write the info on it from time to time, but if you analyse for each dive, what’s the difficulty in doing fresh marking?
 
For me, only deco or stage bottles have permanent markings. My back gas tanks do not. They are only marked with an analysis tape. You can't read it while you're diving them anyway.

I have 2 AL80s dedicated to 50% O2, one AL80 dedicated to 32% Nitrox as a stage, and when I get one, I'll have one AL40 dedicated to 100% O2. So far I've been borrowing. I don't use another deco gas than 50% or 100%.

Recently I did have to put 50% in the 32% marked stage. I put a temporary set of "permanent" markings on. That's the way my instructor taught us and it works for me.

If you only have 1 AL80 and you frequently change what's in it, then some type of duct tape marker might work better for the MOD. I think the mailbox numbers look nicer, and you want them easily readable by your teammate for gas switches. DGX also does sell MOD numbers as JohnnyC pointed out. I just don't like their font. I'm picky about fonts.
 
So if you put permanent numbers MOD stickers on the side of your tanks, how do you adapt when you change the mix?
This is a valid question for your back/travel gas and your deco gas.
I was instructed to always use the best mix for your back gas, which can change on each dive. Shouldn’t you alway try for the best mix? Additionally, your deco gas should also be matched as per the dive and not pigeon yourself to only 1 mix because your tank is marked as such.

I much prefer tape on both the neck and side. I never had a tank that the sticker rubbed off in fresh or salt water. Of course you have to write the info on it from time to time, but if you analyse for each dive, what’s the difficulty in doing fresh marking?
Prior to permanent marking stickers, I’ve had crappy analysis tape from various shops peel/get scraped off during penetration. There are no valid arguments against non standard deco mixes and most would disagree with your instructor on that one.
 
Prior to permanent marking stickers, I’ve had crappy analysis tape from various shops peel/get scraped off during penetration. There are no valid arguments against non standard deco mixes and most would disagree with your instructor on that one.

so how does that account for your side mounted travel and back gas? Especially since those bottles are next to your deco gasses.
 
so how does that account for your side mounted travel and back gas?
Stage bottles are permanently marked. On CCR I’m not often in the habit of needing a travel gas but that too would be permanently marked and a constant mix. Doubles are standard gasses and marked with analysis tape on the inboard side of the crown. Any cylinder that can be passed or clipped off gets DGX or mailbox MOD stickers and day-of analysis tape on the crown for redundancy.
 
I was instructed to always use the best mix for your back gas, which can change on each dive. Shouldn’t you alway try for the best mix? Additionally, your deco gas should also be matched as per the dive and not pigeon yourself to only 1 mix because your tank is marked as such.

This has been extensively covered many times but in a nutshell

The value of best mix is very low, at most 5 mins less deco vs a standard mix (eg 21/35, 18/45)
The value of standard mixes is that its easy to get so familiar with them that you intuitively know your deco. Which is a huge plus long term and in crisis situations.

Bad thing about best mix is if you get blown out you are stuck with that MOD until you can go back. Ditto if you get a last minute change of plans. South side of the island is blowing a gale but the north side is calm - the wreck just happens to be 15ft deeper. ruh oh. Standard mixes give you way more flexibility for a tiny lack of optimization.
 
This has been extensively covered many times but in a nutshell

The value of best mix is very low, at most 5 mins less deco vs a standard mix (eg 21/35, 18/45)
The value of standard mixes is that its easy to get so familiar with them that you intuitively know your deco. Which is a huge plus long term and in crisis situations.

Bad thing about best mix is if you get blown out you are stuck with that MOD until you can go back. Ditto if you get a last minute change of plans. South side of the island is blowing a gale but the north side is calm - the wreck just happens to be 15ft deeper. ruh oh. Standard mixes give you way more flexibility for a tiny lack of optimization.

I’m still surprised that we have questions about best mix/standard gasses.... ESPECIALLY for deco gas...

80’s are cheap and 40’s are even cheaper, keep dedicated bottles for dedicated gasses...
 
So if you put permanent numbers MOD stickers on the side of your tanks, how do you adapt when you change the mix?
This is a valid question for your back/travel gas and your deco gas.
I was instructed to always use the best mix for your back gas, which can change on each dive. Shouldn’t you alway try for the best mix? Additionally, your deco gas should also be matched as per the dive and not pigeon yourself to only 1 mix because your tank is marked as such.

I much prefer tape on both the neck and side. I never had a tank that the sticker rubbed off in fresh or salt water. Of course you have to write the info on it from time to time, but if you analyse for each dive, what’s the difficulty in doing fresh marking?

The short answer re:markings is, backgas doesn't require MOD markings beyond analysis tape because your backgas may change, regardless of whether you're using standard gases or not.

The short answer re:best mix is, best mix sucks and is rarely the best for anything except some very limited circumstances. Start diving standard gases and don't look back. This has all been covered pretty significantly here and elsewhere.
 
https://www.shearwater.com/products/perdix-ai/
http://cavediveflorida.com/Rum_House.htm

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