T5 Vs T8

[Bobtastic]

Hi all,

I've been reading up on planted tanks and it always appears that T5 lighting is prefered to T8 but I'm not sure why that is? Can someone explain it to me?

Thanks in advance!

 

[Gav935]

T5 bulbs are more powerful than their equivalent length T8, they produce a brighter,more intense light that is better at penetrating deep water than T8s. They are also different thicknesses (the exact dimensions escape me) therefore require their own specific ballasts.

 

[Bobtastic]

Thanks! How do I go about calculating the watts per gallon? Is it as simple as adding the wattage of the number of bulbs and then dividing it by the gallonage? Maths was never my strong point.

 

[SuperColey1]

T5 bulbs are more powerful than their equivalent length T8, they produce a brighter,more intense light that is better at penetrating deep water than T8s. They are also different thicknesses (the exact dimensions escape me) therefore require their own specific ballasts.

Not necessarily!!!

T5 should not be confused with T5HO.

T5 tubes are almost the same wattage as T8 equivalent lengths. A little more not much though. They are slightly more intense. All different diameters require different type of ballasts T8 needs a T8 ballast, T12 needs a T12 ballast etc.

T5HO is about double W for the same length. They specifically require electronic ballasts due to the way they are 'overdriven'. They will be much more intense underneath the tube than a T8 or T5, however the T8 and T5 will produce more light for the same watt (dependent on quality of tube, ballast CRI, K etc.)

By that I mean to get the same W in T8 or T5 you would need double the tubes. Their total output would however be higher.

AC

 

[Bobtastic]

Ok, you've just confused the heck out of me!

The details on the website simply says T5 Lighting: 2 x 39watt. Not sure which type they are or if they are of different colours/temperatures.

 

[three-fingers]

When you say you need different ballasts for different thickness of tubes, is this just because of the connectors? Because I've been plugging T8 tubes into old T12 ballasts for years and not noticed any issues, this hasn't been a fire hazard or anything has it?

And if I changed the connectors, could I plug a regular T5 (not T5HO) into the right wattage T8 or T12 ballast?

Also, when you say regular T5's aren't much better than T8's, is this accounting for their extra efficiency when used with reflectors too?

 

[Gav935]

Supercoley is correct, I was only talking about T5HO's, I forgot that there were normal T5s too. Though I think (someone please correct me if I'm wrong) most aquarium t5 applications are of the HO variety.

 

[Bobtastic]

Now I'm even more confused... So is it only the T5HO's that are better than the T8's? Are the "normal" T5's pretty much the same as T8's then, do they look the same? Like I said the tank I have been looking at is listed as have T5 Lighting: 2 x 39watt, they are a lot narrower than the bulbs I have in my current tank which I know are T8's.

 

[SuperColey1]

When you say you need different ballasts for different thickness of tubes, is this just because of the connectors? Because I've been plugging T8 tubes into old T12 ballasts for years and not noticed any issues, this hasn't been a fire hazard or anything has it?

Also, when you say regular T5's aren't much better than T8's, is this accounting for their extra efficiency when used with reflectors too?

T5 will be slightly better than T8 but not a huge amount. If you look at the ballast it will have the type of tube it should be used with on the rear. Funny I posted this pic up earlier for someone on barrreport. lol so I haven't had to search for it:

Look at the printing and it clearly reads 4X32T8 (4 x 32W T8) in the model No. It then details below it which tubes and combos can be run with the ballast. They are all T8s!!! This is an extreme example as most ballasts will not detail combos etc. My T8s just say 1X18T8.

http/www.servicelighting.com/catalog_pro..._number=SL49857

No idea if you have afire hazard on your hands. Check it out with the electrical savvy lot in the hardware section Maybe just a way of not having cheap universal products to keep a price somewhere above 1p or it may be something less cynical

The reason that T5 is much more efficient than T8 statements have built and built is because virtually all T8 setups are using electrical (magnetic) ballasts whereas all T5 setups use electronic ballasts. The ballast is the huge efficiency gain. Not so much efficiency gains in light from the tubes (because standard T5 is less light per inch in general) more in wastage efficiencies. they don't get so hot etc.

However if like me you use T8 on electronic ballasts (not electrical/magnetic) then they are as eficient.

T5 being a smaller diameter will have (when used with good individual T5 reflectors) much less restrike. there are much better reflectors available for T5 than for T8 although I wouldn't think there would be too much gain from using standard curved (Arcadia/Juwel) types.

Also being smaller then the light they give will be much more intense directly below

And if I changed the connectors, could I plug a regular T5 (not T5HO) into the right wattage T8 or T12 ballast?

Only if your T8/T12 is using high frequency electronic ballast(s) If it is magnetic/electrical then No. How can you tell?

The electronic is a square box and wires go direct to the end caps (Not via cylindrical starters) The electrical/magnetic goes to circular starters and then the end caps.

The details on the website simply says T5 Lighting: 2 x 39watt. Not sure which type they are or if they are of different colours/temperatures.

They are T5HO I would guess from the wattage oyu have given.

As an example of 863mm (ish) tubes:
T12 - 900mm - 30W
T8 - 900mm - 30W
T5 - 863mm - 21W
T5HO - 863mm - 39W

You can see that for 3ft(ish) tubes T8 and T12 provide more W. T5 provides more Lumens for the watts though!!! Confused

Being so much thinner T5 (5/8ths of an inch diameter) gives more intense light so that to the human eye it looks much brighter. However Lumens is a measurement of how bright something appears to the human eye and NOT how much actual USEABLE light is being emitted. Therefore it may look brighter but could actually be giving out less useable light. Scratch head time folk (T8 is 8/8ths - 1 inch diameter, T12 is 12/8ths - 1½inches diameter)


T5HO gives out a fair bit more light than similar sized T8s - about 30% more - and because of the thin diameter it is much much more intense light but again is it giving out more light? I'm not sure whether it is the tubes themselves (which I doubt) or the fact that most T5HO applications have far superior reflectors than their T8 rivals which makes them so much more light.

That being said there is no doubt that the T5HO setups produce much more light than their T8 equivalents (as in if you want 2 tubes) but that is not necessarily a good thing especially for a beginner in planted. Even some of the more experienced are now choosing to use T8 so they can space their W out rather than pack it into small areas using higher power tubes. This was/is the problem with CF/PL lights (the u bend types)

AC

 

[three-fingers]

And that all goes even further to explain why the 36W bent tube T5 (driven by a magnetic ballast) on my tank just isnt as effective as the 2 x 18W T8's (electronically driven) also on the same tank.

I had initially hoped that the extra light from a T5 tube would make up for it's inefficient shape, but being T5 instead of T5HO, that explains why thats clearly not the case after a couple of years of using the setup.

The amount of heat generated by both the magnetic ballast and bent tube compared to the T8's is just ridiculous too.

All makes perfect sense now. Cheers.

 

[SuperColey1]

Just your quote put alongside one of my comments from the previous post. Remember if someone talks about T5 they mean linear (not bent). U bend or 'twin' compact are referred to as PC or CF or PL:

Yours:
36W bent tube T5

Mine:
Even some of the more experienced are now choosing to use T8 so they can space their W out rather than pack it into small areas using higher power tubes. This was/is the problem with CF/PL lights (the u bend types)

Ally that to the fact that there are nigh on ZERO reflectors available specifically for Compact lighting. What is available is not very good no matter what their manufacturers/owners tell you!!! Loads of restrike and lots and lots and lots of heat!!!


If I went back to fluoros I would definately use T8 on electronic ballasts. Probably 2 or 3 x 18W(24") rather than 1 or 2 T5HO x 30W(29")

On my 33USG that would mean I would use 36 or 54W of T8 rather than 30W or 60W of T5HO. Why? So I could use more tubes to spread the light out over the tank rather than loads of light in one area.

The larger the tank the more important IMO it is to have spread so if your tank was 3 ft depth then you don't want T5HO in a 10" depth luminaire over the centre of the tank when you could've used 5/6/7 T8s and spread them from front to back!!!

Yes intensity is important but not to the point of blinding light. Spread is just as important. Good spread means you can use less intensity.

AC

 

[three-fingers]

Yep, know what you mean.

I went for 2 x T8s in a luminaire for my 30" planted tank - more than enough anyway.

 

[SuperColey1]

Just to clarify a little point. I used to have a 55W CF and to my memory it was 21" long including the connector. That would suggest to me it was indeed T5HO!!! That is going by the 34" long T5HO being 39W compared to the 21W of the T5 standard (or T5NO)

Mine did have an electronic starter however. You say yours is 36W and runs on magnetic? What length is yours (if you don't mind me asking ) That would suggest a T5HO CF being run on magnetic which seems strange and contrary to all the reading I have ever done on T5HO Maybe that was a fire hazard indeed

On the people talking about T8 vs T5 and T5HO debate. Most of these storys came up when people upgraded to T5 or T5HO. They weren't standard at the time. The thing was that a lot of tank manufacturers were underpowering their lights by using slightly lower powered ballasts whilst putting 'supposed HO' T8 tubes in there.

I discovered whilst upgrading my Fluval Duo Deep tank's canopy that although it had Hagen's T8 'HO' 20W tubes that the ballast was actually a magnetic 2x15W. So not only was it not 40W as the tubes said. It was only running at 30W.

A friend's Duo Deep 1200 had a 2x30W ballasts in. This was for 4ft 36W tubes!!! That meant instead of 72W it was only being run at 60W

So imagine this theoretical situation:
The owner decides that the T8s aren't cutting it. 2 x 4ft 36W (72W) of T8 are growing but looks a little dull.

Decides to upgrade to 2 x 28W (56W) (1149mm nearly 4ft) T5 linear (standard or NO) looks much brighter and the plants are still doing OK even though he's reduced wattage from 72W to 56W

How is this possible he asks himself? These T5s must be surpassing the T8 by a country mile!!!

In reality he downgraded from 60W to 56W. Not a lot. Running a tube that far below its max will mean it does indded look pretty dim. The Lumens output is indeed higher on T5 than for T8 but that is what humans can see. PAR data difference? I haven't found much detail on it.

From my T8 experience I know that the same T8s on the original magnetic 15W underpowered ballast were much poorer than on electronic 18W ballasts by a considerable margin!!!

The difference was immeasureable. I would guess a fair amount was upgrading from magnetic to electronic but most of that improvement would be from running the tubes at their max rather than underpowering them. The K was also much more accurate.

This is always worth anyone checking out prior to an upgrade. If you have an old setup using T8 and you want more. A simple upgrade would be to check if the ballast is magnetic and/or underpowered. If so replace it with electronic at the correct wattage rating. Not only will it improve things drastically. You can then forget the 'replace your tubes 6monthly/yearly' statement. They will last as much as 8000 hours with only 5% loss of performance!!!

£10 for a ballast versus using tubes for 2,3,4x as long. Will be a saving and an improvement either way

AC

 

[three-fingers]

Now you've got me considering opening up my perfectly functional T8 Arcadia luminaire I bought new in October and replacing the ballasts with electronic ones. I have enough light as it is, but I just like the sound of better efficiency lol. Also save money on buying new tubes...hmmm.

My 36W T5 power compact ballast is the Interpet ones they don't make any more. It gets very hot and has a cylindrical starter. The glass in the bulb is 15" long and another 1" for the white plastic connector bit at the bottom.

I have to buy a new bulb roughly every 6 months because it stops working (shows the black burnt bits at the base).
Also the end cap part looks as if its actually melted .

 

[SuperColey1]

On the Arcadia I am surprised their 'new' luminaires have magnetic in!!!. Cheap electronic ballasts can be bought off ebay for £5 - £10 but you have to get the right one. they are listed as I showed in the pic in the post above. Buy the one that matches your tubes W & Qty. i.e. if you have 2 18W tubes don't by a 1X36W get a 2X18W.

Your Interpet CF was the original one. They then changed the ballast box to electronic which is the one I had. they then got banned due to the vent design on the box

Here is where I got the '95% after 800ohours statement' from. It does deal with Lumens which mean nothing but you can see that T8 and T5HO on electronic ballast are pretty comparable both on output lumens (4xT5HO v 6 x T8) Both beat MH for much less wattage!!! Long page this I pressed page down 15 times to get to the comparison chart The whole article is worth reading if you have the time.

This is the sort of electronic ballast you get off ebay. I have a 1 x 18W version of this one and it has been running the same tube for the last 2½ years Currently (Since March) for 16 hours a day over an emersed setup. lol

[URL="http/cgi.ebay.co.uk/Tridonic-2-x-18w-T8-...:0|293:1|294:25"]http/cgi.ebay.co.uk/Tridonic-2-x-18w-T8-...:0|293:1|294:25[/URL]

AC