I have a "GE" well made for them
and one ballast is bad (It has two F8T5 lamps each with it's own ballast)
I believe it was instant start as it turns on with no delay, But after a few seconds I see a blue flash from the ends of the tubes, Why is that?

But I have heard that there is many different types of ballasts and ways of starting the lamp. Some I know of are
I know the names of the method but I want to know how it works and the difference between them

Instant start
Programed start
Rapid Start
Trigger Start
Programmed Rapid Start
and good Ol' pre-heat start or switch start (As it is called over seas) but
I would say that all Fluorescent lamps are Switch Start as the tubes start when you flip the Switch 

I received a ballast from don93s and I plan to replace both ballasts with a single ballast
Thanks for the ballast don93s
will the ballast I received run a single lamp?
It is a KeyStone KTEB-208-1-TP-SN-MW
I can't seem to find any info on this exact ballast but I did find the specs for a similar one 
the KTEB-208-1-TP-SL-MB

Thanks all

Greetings. 

I took this from wikipedia.  It seems to echo what most say on here and when I asked the same question you did. I prefer the Rapid Start and mostly the Programmed Start for the environments I deal with.  Instant Start works best for environments where the bulb will be turned on and left on for a long period of time.  Since installing a few programmed/delayed start ballasts in a few of the fixtures I work on that see on/off operation several times a day, I've begun to notice an increase in lamp life.  It really only takes almost 2 seconds from the time I switch on to when the lamps turn on so that is something I can deal with just fine.  I am quite pleased with the Sylvania, GE, and Universal brand ballasts thus far, and I use Sylvania the most right now. 

Instant start

An instant start ballast does not preheat the electrodes, instead using a relatively high voltage (~600 V) to initiate the discharge arc. It is the most energy efficient type, but yields the fewest lamp-start cycles, as material is blasted from the surface of the cold electrodes each time the lamp is turned on. Instant-start ballasts are best suited to applications with long duty cycles, where the lamps are not frequently turned on and off.
Rapid start

A rapid start ballast applies voltage and heats the cathodes simultaneously. It provides superior lamp life and more cycle life, but uses slightly more energy as the cathodes in each end of the lamp continue to consume heating power as the lamp operates. A dimming circuit can be used with a dimming ballast, which maintains the heating current while allowing lamp current to be controlled.
Programmed start

A programmed-start ballast is a more advanced version of rapid start. This ballast applies power to the filaments first, it allows the cathodes to preheat and then applies voltage to the lamps to strike an arc. This ballast gives the best life and most starts from lamps, and so is preferred for applications with very frequent power cycling such as vision examination rooms and restrooms with a motion detector switch.
Hybrid

A hybrid ballast has a magnetic core-and-coil transformer and an electronic switch for the electrode-heating circuit. Like a magnetic ballast, a hybrid unit operates at line power frequency—60 Hz in North America, for example. These types of ballasts, which are also referred to as “cathode-disconnect ballasts”, disconnect the electrode-heating circuit after they start the lamps.

From the reading, a hybrid ballast, is essentially a preheat ballast with an electronic starter. The Eltam Perfect-Start B and the Shaingout Electronic-Start, are of this type. Any preheat ballast can be converted to a hybrid one, by replacing the glow starter with an electronic starter (For example Arlen Pulstarters).

The british have two variations of rapid-start ballasts: semi-resonance start ballast and quickstart ballast.
The difference between the SRS and the RS ballasts, is that SRS uses the capacitor for generating OCV for starting rather than the autotransformer of the RS ballast. Its starting also looks different.

The cheap electronic ballasts we have in Israel in household fixtures and CFLs, are actually rapid-start ballasts (Cathodes heated during ignition and operating by passing current). However the starting process is so fast, that the lamp starts before the cathodes was enough to heat, so the lamp instant starts with cold cathodes but operates with hot cathodes. I call this starting "Instant rapid-start".

The cheap electronic ballasts in the US, are instant start. It is the most efficient type, because of no loses on the cathodes and also simplicity of the system. Most emergency inverters of fluorescent emergency lighting and exit signs in Israel, are from this type, and indeed you can see that the cathodes become black after little use (The lamps operates with cold cathodes and dimmed during a power interruption).

Some of this may be helpful as well as taken from Wikipedia:
http://en.wikipedia.org/wiki/Fluorescent_lamp

Fluorescent lamps with magnetic ballasts flicker at a normally unnoticeable frequency of 100 or 120 Hz and this flickering can cause problems for some individuals with light sensitivity, they are listed as problematic for some individuals with autism, epilepsy, lupus,chronic fatigue syndrome, Lyme disease, and vertigo. Newer fluorescent lights without magnetic ballasts have essentially eliminated flicker.

Fluorescent lamps using a magnetic power line frequency ballast do not give out a steady light; instead, they flicker at twice the supply frequency. This results in fluctuations not only with light output but color temperature as well, which may pose problems for photography and people who are sensitive to the flicker. Even among persons not sensitive to light flicker, a stroboscopic effect can be noticed, where something spinning at just the right speed may appear stationary if illuminated solely by a single fluorescent lamp. This effect is eliminated by paired lamps operating on a lead-lag ballast. Unlike a true strobe lamp, the light level drops in appreciable time and so substantial "blurring" of the moving part would be evident.

In some circumstances, fluorescent lamps operated at the power supply frequency (50 or 60 Hz) can also produce flicker at the same frequency itself, which is noticeable by more people. This can happen in the last few hours of tube life when the cathode emission coating at one end has almost run out, and that cathode starts having difficulty emitting enough electrons into the gas fill, resulting in slight rectification and hence uneven light output in positive and negative going AC cycles. Power frequency flicker can also sometimes be emitted from the very ends of the tubes, if each tube electrode produces a slightly different light output pattern on each half-cycle. Flicker at power frequency is more noticeable in the peripheral vision than it is when viewed directly, as is all flicker (since the peripheral vision is faster—has a higher critical frequency—than the central vision).

Near the end of life, fluorescent lamps can start flickering at a frequency lower than the power frequency. This is due to a dynamic instability inherent in the negative resistance of the plasma source,which can be from a bad lamp, a bad ballast, or a bad starter; or occasionally from a poor connection to power.

New fluorescent lamps may show a twisting spiral pattern of light in a part of the lamp. This effect is due to loose cathode material and usually disappears after a few hours of operation.


Fluorescent lamps using high-frequency electronic ballasts do not produce visible light flicker, since above about 5 kHz, the excited electron state half-life is longer than a half cycle,[citation needed] and light production becomes continuous. Operating frequencies of electronic ballasts are selected to avoid interference with infrared remote controls. Poor quality (or failing) electronic ballasts may have insufficient reservoir capacitance or have poor regulation, thereby producing considerable 100/120 Hz modulation of the light.

I'd love to know what Trigger Start is, been trying to find some information on this but so far without any luck. We don't appear to have this starting method in the UK/Europe.


BG

I found this guide fluorescent ballast types
It does not explain the blue flash I see from the ends of the tube with the instant start ballast though. Does anyone know why that happens, also it looks like it can't be good for the tube

Blue flashes or glow at the ends of the lamp = cold cathodes operation. This isn't good for the electrodes life.
An instant start ballast, start the lamp with cold cathodes and relys on the discharge itself to heat the electrodes, much like LPS and HID lamps. The instant start ballast is essntially an autoleak transformer for fluorescent lamps instead of low pressure sodium lamps, as both the LPS autoleak transformer and the fluorescent instant start ballast operates with the same manner.
Therefore, I think that single pin lamps should have the same beehive electrodes as LPS lamps have, which can better survive cold cathode starting, what isn't happens in reality.

BG,

Trigger start is literally exactly the same as rapid start. It's rapid start for lamps 20 watts and under. Only difference is the cathode heating voltage is around 9 volts, whereas rapid start (lamps over 20 watts) is around 3.5 volts.