Dive Computer Expert Reviews
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Tusa Zen IQ–900 is made in a classic dive watch computer style. It has 4 dive modes and fully functional digital watch, so you may use it not only underwater but also wear Zen onshore. Even though it has advanced features and functions that may be welcomed by advanced divers and guys who do freediving, this dive computer can be used successfully by the beginners in diving activities as well.
In July 2010 Tusa released a firmware update to fix some glitches and improve performance of Tusa Zen IQ–900 dive computer. This update can be downloaded from Tusa website.
Copy this Tusa ZEN IQ-900 Key Features & Alarms Card for your Reference and Share with your friends and buddies!
Above mentioned alarms are for Air and Nitrox dive modes, FREEdiving mode has its own alarms and we will discuss them later in following sections.
Tusa Zen IQ-900 has 4 control buttons on user interface and 3 bar graphs for graphical representation nitrogen loading, ascent speed, and oxygen toxicity. These bar graphs will be familiar to you if you used before dive computers from Aeris or Oceanic. If you didn’t – no problems, it easy to interpret their meaning. Brief descriptions each of them you may find below:
Display has main and alternative screens, so you need to press ADVANCE button to move between them to view additional dive data.
I may say that buttons are quite big and easy to press, digits are big too – no problems for viewing and backlight is strong enough – so there should not be any troubles during diving with Tusa Zen IQ-900.
All adjustable functions are divided to certain groups and will be familiar to you if you used Oceanic dive computers before.
Copy this Tusa ZEN IQ-900 Fine-Tuning Card for your Reference and Share with your friends and buddies!
It is useful and convenient to plan repetitive dives and Tusa Zen IQ–900 has a special function for this – Plan Mode. Using this mode you may see calculated No-Decompression Times for your next dive, according to nitrogen and oxygen toxicity levels from your previous dives (if any).
Setting water activation to ON before diving and Tusa Zen IQ-900 will activate dive mode when it senses depth of 1.5 meters.
Tusa Zen IQ-900: Diving With Air & Nitrox
Copy this Tusa ZEN IQ-900 No-Decompression Displays Card for your Reference and Share with your friends and buddies!
During No-Decompression dive Tusa Zen IQ-900 may give us Deep and Safety stops prompts upon reaching certain conditions. There is no any penalty applied if we miss Deep and Safety stops, because they are recommended and not compulsory. But it is a good idea to complete them just to be on the safe side!
It is worth to say about upgrade from Tusa here. Safety Stop prompt used to show depth of 4.5 meters before, but now with new upgrade Safety Stop depth will be 5 meters.
As this dive computer allows using 2 Nitrox gas mixes, we may swap mixes during a dive, of course, if we enabled 2nd gas mix. It is easy procedure, and if you want to change to gas mix with higher PO2 than allowed – Tusa Zen IQ-900 will warn you by giving audio alarm and displaying certain message.
Tusa Zen IQ-900 activates Decompression mode, if we exceed our No-Decompression Limits (NDLs). Upon entry into this mode you will hear an audio and applicable dive data will be displayed. From this moment all calculations will be made regarding to Decompression mode. Following information will be displayed:
Decompression display has main and alternative screens and above is a summary of what we get. To move around displays – use ADVANCE button.
During decompression, diver may create, so called violations, which happen if he/she ascends shallower and stays for some time above the displayed decompression stop depth, or diver may descend deeper than Maximum Operational Depth (MOD), or decompression requires ceiling depth range between 18 m and 21 m deep.
Tusa Zen IQ-900: Diving In GAUGE Mode
Next Dive mode of Tusa Zen IQ–900 is Gauge. Dive computer doesn’t perform any calculations of nitrogen and oxygen loading and decompression condition. It can be used as a depth gauge and timer only. As with other dive computers, after diving with this one in Gauge mode, you need to wait 24 hours before you may use it for diving with Air or Nitrox.
Display shows dive data similar to listed below and it is a summary from main and alternative displays:
Tusa Zen IQ-900: FREEdiving
Other Dive mode of Tusa Zen IQ-900 is FREEdiving. People who do freediving may be particularly interested in this one, because it has set of functions that may satisfy well this sort of diving activity!
Along with its own functions, Freedive mode shares some settings with Air and Nitrox dive modes, like time and date, Personal Conservative Factor settings and backlight duration.
Dive computer calculates nitrogen loading according to Air by default and the residual amount that you may have left between diving with Air, Nitrox and this freediving.
Special settings and alarms for freediving can be accessed and set from Free Surface mode. We may set following functions and alarms:
During freediving display shows following dive data (summary from main and alternative displays):
And that’s for sure – you will meet freediving alarms that you set before – Dive Time alarm and Free Depth alarms with all appropriate data displayed and stored in on-unit memory for further downloading to PC.
There is another type of Freedive alarm – Free NiBG alarm. This one activates when nitrogen remained from previous dives and current nitrogen loading hits the Caution zone. It may even happen when nitrogen level will increase to Decompression condition.
Freedive data can not be displayed by this dive computer – you need to buy optional PC interface cable and download software from Tusa website to view and organize freedive data on your PC.
After we went through all dive modes of this dive computer – it is time to review our Logs, History, download data to PC (who has interface, of course!), or maybe plan subsequent dives.
Below is a summary of Tusa Zen IQ-900 functions that may be accessed on surface after the Transition period (10 minutes after the dive):
Tusa Zen IQ-900: What Divers Say
I reckon Tusa designed and produced pretty decent dive computer that can compete in nowadays scubadiving market and win!
Though it is very similar to some Oceanic models – it still has its own personality and distinctive features, like large digits that are easy to read underwater; dual nitrox gas mix; automatic altitude setting; data retention function and some others.
We didn’t have and didn't notice any troubles while diving with Tusa Zen IQ-900 dive computer. Buttons were easy to press and display was clearly readable. All decompression and conditional violation data was managed smoothly as well.
From the specs, features and price point of view I think Tusa Zen IQ–900 can be definitely a winner!