MY 250W DE MH project

[Creetin]

No no, credit is all yours! I only pointed you in the right direction! I think you did an excellent job!

nah. i had a good guide, tts for sure! thanks!

[dr evil]

hi bro,

well done.......only some thing to comment in the diy.

1)the 250watts de holder should have a free play......as the bulbs will expand during operations. if u look a the holder properly, how hard u tighten, it will not get tighten to the reflector. If u get it wrong, the bulb will explode after firing up...

2)u should have fans for ventilations......ur water can easily get heat up.....

cheers.......diying urself will save u $$....but make sure u have all the necessary precaution....dont want to burn the houses down... j/k

again....well done

[roidan]

er...tempered glass is one thing....is the tempered glass able of UV shielding?

tempered glass is to prevent sudden crack and breaks of your glass when your tank water accidentally splashes on the glass....but if this tempered glass is not UV shielded, your corals will get burned by UV from the DE bulb...

not all tempered glass are properly UV shielded

hope yours is

[keithtty]

250W DE MH parts:

1. 1 pair of 250W DE holder

2. 1 length of black wire

3. 1 length of 3 core wire

4. some plastic connectors

5. the ballast, capacitor, ignitor and wat-nots are all in that black box.

Where to get it?

THE LIGHT SHOP

No. 73 Jalan Besar

S 208817

Tel: 6295 8431

Email: thelightshop73@hotmail.com

Cost: $150 (excluding the 3 core wire)

Hi Creetin,

Nice thread on your DIY project. Does the ballast, capacitor, ignitor come ready assembled in that black box or does that need to be self assembled too? Thx-Keith

[ervine]

Great DIY man!! It's a lot sleeker than my 250W SE from Viclite

[JuzzMarine]

Good effort!!! Nice work!!!

Ever thought of hiding the wire that come out from the MH holder? Maybe you can drill a hole on the reflector for the wire to pass thru, running between the reflector and the casing?

[Creetin]

hi bro,

well done.......only some thing to comment in the diy.

1)the 250watts de holder should have a free play......as the bulbs will expand during operations. if u look a the holder properly, how hard u tighten, it will not get tighten to the reflector. If u get it wrong, the bulb will explode after firing up...

2)u should have fans for ventilations......ur water can easily get heat up.....

cheers.......diying urself will save u $$....but make sure u have all the necessary precaution....dont want to burn the houses down... j/k

again....well done

Hi Dr Evil... thanks for the advice!

1) yes i noticed e screws do not hold too tightly. e light has been in operation for 5 days so far and no problems. i certainly dunwan it to explode! the holes i drilled for the holder are slightly bigger too, not tat i anticipated the issue of free play but rather a not too precise drill job. thankfully, e aluminum material is quite forgiving.....

2) i added a fan oredi. but i have a chiller for mi water too...

once again, thanks for your invaluable advice...

[Creetin]

Hi Creetin,

Nice thread on your DIY project. Does the ballast, capacitor, ignitor come ready assembled in that black box or does that need to be self assembled too? Thx-Keith

yes, the ballast, capacitor, ignitor come ready assembled in that black box. no nid to do anithing at all. just plug and play.....

[Creetin]

er...tempered glass is one thing....is the tempered glass able of UV shielding?

tempered glass is to prevent sudden crack and breaks of your glass when your tank water accidentally splashes on the glass....but if this tempered glass is not UV shielded, your corals will get burned by UV from the DE bulb...

not all tempered glass are properly UV shielded

hope yours is

to be honest i dunno! heh.....

but so far mi corals look fine..... is there any kick in for UV to burn corals? few days? weeks? or just few minutes will do?

[Creetin]

Good effort!!! Nice work!!!

Ever thought of hiding the wire that come out from the MH holder? Maybe you can drill a hole on the reflector for the wire to pass thru, running between the reflector and the casing?

yes i tot about that. but just too difficult cos e wires are too short. if u wana do that, den u got to think of a way to connect e wires behind e reflector while e reflector is in e casing! too much trouble.....

[Cedric]

er...tempered glass is one thing....is the tempered glass able of UV shielding?

tempered glass is to prevent sudden crack and breaks of your glass when your tank water accidentally splashes on the glass....but if this tempered glass is not UV shielded, your corals will get burned by UV from the DE bulb...

not all tempered glass are properly UV shielded

hope yours is

Actually I beg to differ, I believe all glass will block UV. I'm using a normal tempered glass for my MH for a good 3 years. So far so good.

Normal Glass

Most standard silicon glass absorbs or otherwise limits the passing of UV. This is why you really can't get a suntan through the window.

I could not have said it any better! you dont need any special glass, regular glass will protect against UV. Fopr those that dont think they need UV protection on DE bulbs if they have thier face up to the tank like most of us do they will be needing a seeing eye dog on a year or two. If they just have the light unprocted but do not look directly at it, well it may be a few years later but the white cane will come. Now if you have small children who are at eye level with most tanks, why woudl you even tank that chance

IceCap's Comments

From IceCap:

Any glass will cut out most of the UV. Tempered glass is safer as it's much less likely to shatter. Temper glass with UV A+B block is the best you can get, especially if you have a situation where the light from the pendant is directly visible to you or a child looking up at the tank.

I've attached two comments I've found on reefcentral which might prove useful.

When I started with my own diy MH hood, my normal 3 mm glass was working fine (i.e. no corals got burnt or anything) till it shattered when I accidentally splashed water on it. In less than 2 hours my corals were literally fried and all my fishes were hiding. Since getting my tempered glass, things got back to normal. Therefore, if the glass is not providing enough sheilding, you will be able to tell easily in a matter of hours if not less. Hence I hope this will help convince some of you by my personal experience of using normal tempered glass without UV coating is sufficient.

[Tigger]

nice and neat

[roidan]

all glass will block UV, but to varying degrees mah

oh...i always tot uv glass has a special UV blocking coating on it..

i read some museum art pieces use expensive UV glass that blocks almost all of the UV spectrum to ensure that the art pieces do not face discoloration from sunlight or museum internal lighting..

hmm....in that case, probably those museums could have just used normal tempered glass and save the money..hehe..

never mind...they are well funded

what i am afraid is that because of the presence of UVA, UVB and UVC,

normal tempered glass only filters them to some degree, whereas in proper uv-filter/block glass, the filtering is of a higher degree and thus preventing the socalled harmful UV spectrum.

but since the corals are doing well, i guess the corals can tahan some degree of the spectrum without ill effects

[roidan]

From IceCap:

Any glass will cut out most of the UV. Tempered glass is safer as it's much less likely to shatter. Temper glass with UV A+B block is the best you can get, especially if you have a situation where the light from the pendant is directly visible to you or a child looking up at the tank.

You may want to post this on the main board or search the topic as I know this periodically gets passionately discussed.

BTW, contrary to what you'd think, there's more UV danger while the lamps are coming up to full brightness than when firing at full blast.

Andy

icecap feels that tempered glass is the best you can get, when its coated with UV blocking properties....

so this does not make all tempered glass automatically blocking the whole UV spectrum...unless going through another process to make it coated

tempered glass just strengthens the glass against shatttering and even if it does, the broken glass tends not to have sharp edges but does nothing much against blocking the whole UV spectrum, it's just like normal glass....unless it's coated with anti-UV / UV-blocking then it starts to radically cut down the UV spectrum, good and bad

[ben]

wow! U are very good. Nice diy, can considered a real MH light casing bought from shop if the box is hidden.

[roidan]

Hence I hope this will help convince some of you by my personal experience of using normal tempered glass without UV  coating is sufficient. 

yeah..

since some bros like you are having no problems using normal tempered glass on their reef tanks, at least those who wanna diy can just look for any glass maker to cut out suitable size of tempered glass for their projects...

tempered glass, just like normal glass, cut UV to some degree, but it's a matter of how much, especially when the wattage of the DE bulb gets from 150 to 250, the amount of radiation from the more harmful spectrum of the UV gets higher...

so, while it's great to know from your usage that normal tempered glass is able to block 250W DE's harmful radiation through, i am still quite afraid for the long term health of the corals....in fact they may colour up more in response of self blocking of the harmful UV radation, but i dare not take the chance of a 250W DE with a normal tempered glass in a shallow tank...

in a tank of reasonable depth, probably the radiation would have been much lower having gone through the water and especially for the sand bed corals, they probably wun mind

[Cedric]

Hi Roidan,

Actually, from what I've gathered over the years from reefcentral and reefs.org, the point Icecap is trying to tell reefers is that any silica glass will do fine for the purpose of protecting our precious corals against uv from DE bulbs although they do not block 100%. I think the coated ones block up to 99.9%.

Allow me to explain (have to go technical here to clear up the misunderstanding so please bear with me, I'll go as layman as possible):

UV comes in the form of UV-a(380-315 nm) most penetrating and least harmful, UV-b(315-280 nm), and UV-c(280-10 nm). UV-c is the most harmful (same thing our UV units uses to zap the nasties) and fortunately also the most easily blocked. This is why a special material (I believe it to be quartz) must be used to allow the UV-c to pass and kill whatever we want to kill in our UV units. Glass only allow the long wavelengths through and not short wavelengths like UV-c. This is the working principal of greenhouses. See this article

Most importantly, our glass, any glass, blocks 100% of UV-c and lets certain % of UV-a and UV-b passes. However in our aquarium application, the doses of UV-a and UV-b after passing the glass are not enough to have any effects on our corals for normal photo periods. Infact, there were discussions also in reefcentral on SPS reefers trying to increase the amount of UV-a and UV-b penetration to colour up their SPS. The results were however inconclusive.

Yes, indeed, tempering has no effect what so ever on UV filtering, its merely for strengthening the glass against thermal stresses. Tempering is done by heating the glass to extreme temperature and rapidly cooled. This induces a internal tension as the surface chilled faster then the internals making the glass stronger. The principal is similar to pre-stressed concrete. If you are worried that normal glass will not offer you enough protection for the corals, you have two options.

One, increase the thickness. The thicker the glass, the more UV it will block. Basically, if thickness 1x transmits 50% of the UV, thickness 2x will transmit 25%, 3x will transmit 12.5%, and so on.

Two is of course coating it with UV protection. Note that the UV coating protects againt UV-a and UV-b. They seldom mention UV-c because its already blocked without the need of any coatings.

Oh yes, you are right about museum using special museum glass to protect the paintings. Its however different becoz the pigment dyes are not capable of providing UV protection by themselves even against UV-a. Since you need to protect them for like centuries, you need to use the special glass. And mind you, it only blocks 97% of UV-a, UV-b. (And of course 100% of UV-c)

To conclude, I just like to assure you our normal glass is sufficient for our coral protection. The best test if you insist is to ask Creetin after a few years for his experience with his corals.

[roidan]

wah..informative

then again, why can't they coat our DE bulbs with glass instead of quartz just like the SE bulbs? since i think the glass coating on the SE bulbs are cheaper than the quartz on the DE? why dun they save money and save our troubles at the same time? any reason why they chose to use quartz for DE and just glass coating on SE bulbs?

er...then i think this would be great news for hon right? i mean, he need not order from germany his giesemann glass for his 250W pendants already...coz they are probably just normal tempered glass anyway..hehe

He can cut tempered glass the same shape as the giesemann glass? since the UV coating or not will not effect his corals? i think he is going to save a lot of money and can treat you alot of makan liao....

ok, hon, go and get your tempered glass from the glasscutters..forget about germany

[roidan]

but anyway, i also used a 150W DE pendant before on my 2ft last time and i dun think the glass was UV coated, also nothing died within days or months..hehe

but i guess i saw those expensive reef MHs tend to have UV-coated, UV-filter kind of words on their glass, so i began to think it could have a difference...

sigh....so all this UV coating is just bullshit....haha...gee...i fell for such marketing phrases...

so i gather here that the essence is just to have any glass to block the DE bulb...and for added safety, tempered glass is stronger and will not break with sharp edges

[Ian]

This is one of the best "DIY Thread"

Detailed step by step explanation

Detailed pictures

And with good info on the topic of tampered UV glass.

Good Job to all of you involved!

[Creetin]

wah..informative

then again, why can't they coat our DE bulbs with glass instead of quartz just like the SE bulbs? since i think the glass coating on the SE bulbs are cheaper than the quartz on the DE? why dun they save money and save our troubles at the same time? any reason why they chose to use quartz for DE and just glass coating on SE bulbs?

er...then i think this would be great news for hon right? i mean, he need not order from germany his giesemann glass for his 250W pendants already...coz they are probably just normal tempered glass anyway..hehe

He can cut tempered glass the same shape as the giesemann glass? since the UV coating or not will not effect his corals? i think he is going to save a lot of money and can treat you alot of makan liao....

ok, hon, go and get your tempered glass from the glasscutters..forget about germany

hi bro roidan.... FYI, i could only find 12x12inch tempered glass, its the minimum size for tempered glass available locally. But not sure how calciumreef got his...heh....

anyway a 12x12 inch piece typically costs only $28 i think. by 5mm i tink. real cheap.

if u are tinking of tempering and den cutting e glass, it cant be done. its too brittle i guess? e glass factory said it will crack once u try to cut it.

[roidan]

oh yeah..i think glass once tempered...can't be cut...

i think the process is to cut the glass to your desired size first...then go through the process of tempering

if u think of cutting already tempered glass, then very troublesome,

it has to be untempered. To do this it has to be heated in a furnace to close to the melting point and then cooled. Trying to cut or saw tempered will result in it breaking.

[Creetin]

Cedric.... u're the man! wat a very good writeup on the in-outs of e glass-UV relationship!

[roidan]

Tempered Glass

DEFINITIONS

In the production of flat glass the molten silica-based mix is cooled slowly under carefully controlled conditions. This annealing procedure removes undesirable stresses from the glass. Cooling occurs in an annealing "lehr"; hence, the glass is termed "annealed" or "ordinary" glass. Annealed glass which has been heated to a temperature near its softening point and forced to cool rapidly under carefully controlled conditions is described as "heat-treated glass." The heat treating process produces highly desirable conditions of induced stress (described below) which result in additional strength, resistance to thermal stress, and impact resistance.

Heat-treated glasses are classified as either fully tempered or heat strengthened. According to Federal Specification DD-G-1403B, fully tempered glass must have a surface compression of 10,000 psi or more or an edge compression of 9,700 psi or more. Heat-strength glass must have a surface compression between 3,500 and 10,000 psi, or an edge compression between 5,500 and 9,700 psi. The fracture characteristics of heat- strengthened glass vary widely from very much like annealed glass near the 3,500 psi level to similar to fully tempered glass at the 10,000 psi level.

HEAT TREATMENT PRINCIPLE

Glass can fracture when its surfaces or edges are placed into tension. Under these conditions inherent surface or edge fissures may propagate into visible cracks.

The basic principle employed in the heat treating process is to create an initial condition of surface and edge compression. This condition is achieved by first heating the glass, then cooling the surfaces rapidly. This leaves the center glass thickness relatively hot compared to the surfaces. As the center thickness then cools, it forces the surfaces and edges into compression. Wind pressure, missile impact, thermal stresses or other applied loads must first overcome this compression before there is any possibility of fracture.

MANUFACTURING PROCESSES

In the "heat-treatment" process the key procedure is application of a rapid air quench immediately upon withdrawal of hot (approx. 1200 ° F) glass from the "tempering furnace." The immediate and sustained application of an air quench produces the temper. As air direction against hot glass from arrays of fixed, reciprocation or rotating blast nozzles, it is important to extract heat uniformly from both surfaces (uneven heat extraction may produce bow or warp) and to sustain the quench long enough to prevent reheating of the glass surfaces from the still-hot glass core. A quenched condition becomes stable when the glass is reduced to a temperature of approximately 400-600 ° F.

There are two principal manufacturing methods for producing heat-treated glass. One process heat treats the glass in a horizontal position while the second method moves the glass through the furnace in a vertical position with each light of glass held by metal tongs.

STRENGTH

Under wind pressure, tempered glass is approximately four times as strong as annealed glass. It resists breakage by small missiles traveling approximately twice as fast as missiles which break annealed glass. Tempered glass is also able to resist temperature differences (200 ° F - 300 ° F) which would cause annealed glass to crack.

Annealed Glass vs Tempered Glass

Typical Breaking Stress (large light 60 sec. load) 6,000 psi vs 24,000 psi

Typical Impact Velocity Causing Fracture (1/4" light 5 gm missile, impact normal to surface 30 ft/sec vs 60 ft/sec

SAFETY

Fully tempered glass is used in many applications because of its safety characteristics. Safety comes from strength and from a unique fracture pattern. Strength, which effectively resists wind pressure and impact, provides safety in many applications. When fully tempered glass breaks the glass fractures into small, relatively harmless fragments. This phenomenon called "dicing," markedly reduces the likelihood of injury to people as there are no jagged edges or sharp shards.

Fully tempered glass is a safety glazing material when manufactured to meet the requirements of the ANSI Z97.1 Standard and Federal Standard CPSC 16 CFR 1201. Federal Standard CPSC 16 CFR 1201, as well as state and local codes, require safety glazing material where the glazing might reasonably be exposed to human impact. This includes doors, tub and shower enclosures, side lights, and certain windows. Applicable building codes should be checked for specific information and requirements.

[Cedric]

oh yeah..i think glass once tempered...can't be cut...

i think the process is to cut the glass to your desired size first...then go through the process of tempering

if u think of cutting already tempered glass, then very troublesome,

it has to be untempered. To do this it has to be heated in a furnace to close to the melting point and then cooled. Trying to cut or saw tempered will result in it breaking.

Yup roidan and Creetin,

you are absolutely correct that tempered glass cannot be cut once tempered. If you cut it, the surface tension (in your article they use the word compression) will of the tempered glass will be compromised resulting in total complete failure of the structural integrity of the glass. Like the tempered glass on our windscreen, once a chip develops like when you hit a pebble, the surface tension is compromised and it will spread like a massive spiderweb resulting in complete failure.

As for brother Hon, like what Creetin said, too bad the size for his giesemann 250W pendants is too small to find in singapore. The factories (I think got 2) in Singapore tempering glass is fed via conveyer belts into the furnace. The spacing between the chains limits the minimum size of the glass else it will fall right through.