like, could I have a MH bulb in there for rooting / early veg and then swap over to an HPS bulb for flowering?

just exploring my options a bit more.

Hiya Labrat. With my limited knowledge I say no probs. One Fitting but two ballasts (But you would have to put a plug on the cable that cames from your light to your ballasts so you just unplug one and plug the other) or you can obtain a unit that are HPS and MH compatible. Check out this the Aurora Gemene from Canatronics. There should be someone here that knows more on the subject and other alternatives. As you know I will be using a 250w MH for veg but in different room. My freind has just gone 12/12 after veging under his HPS. They certainly went for it compared with the Compact and normal flouros. Another friend always vegs for 2 weeks before 12/12 under a MH. 1 week on 20/4 cycle and then 1 week on 18/6 cycle. He was amazed in the difference in stem thickness and overall growth. This is what convinced me to use MH.
Hope this helps. Please peps correct me if I am wrong. Cheers
Pete

Unless the ballast can take a HPS or MH the answer is NO
most ballasts are either HPS or MH not both
there are some ballast's that can take both type's but there usually more expensive

check your ballast carefully to see what type of ballast it is
and use the correct bulb for the ballast or you'll have problem's
or a potential disaster on your hand's

Hi Labrat
There was a thread going here a while back related to the instructions on how to relocate the ballast on a HID. Think there was a reposting of the link - seem to recall the newer ones from Fastlight - think the IP20 was mentioned.
On the starter there is a label that indicates you can use both.

S.

Thanks for the input all.

I've had a root around for the thread serendipity, but it appears to have disappeared (was it one belonging to the puffer?). I'll search on fastlight though.

Thanks Oldpink. You've answered my next question already. But just to check that I've got this right - switching bulbs would mean rewiring a specific ballast to the reflector, unless I went with a system that was compatible with both MH and HPS. If I did that I'd then have to swap identically rated bulbs (400w MH for 400w HPS)?

Thanks again szark. Those canatronic lights look really appealing and on the Holland Hydroponics site you sent me they do look pricey. But good. Bit of a shame On the plus side it could be all the excuse I need to get a 1000w monster!

Older types of metal halide lamps like the HPI-T types as made by Phillips require a 15% lower voltage/run current than that supplied by a sodium ballast, they will work with a sodium ballast but the run current is higher than it should be so the lamp life is shortened but the lamps will give more lumens.

The newer HQI-T type metal halide lamps as made by venture are designed to run with a standard sodium ballast, they will also run with an old type metal halide ballast but the lumen output will be lower than the lamp spec and the lamp will have a longer life.

Holland hydro are on the dear side IMHO.

I've recently bought a 600w HPS light system from Growell. The box the ballast came in had HPS/MH stamped on it.

So I assume this will work with either bulb?

Thanks OT1, I'd noticed tat Holland Hydro were a tad expensive (and I'm not even Scottish! ).

Sonny, for my info, which system was it?

Super-Nova 600w System plus = £180

thanks sonny.

I've contacted growell to ask them if they stock a light compatible with both bulbs. I'll post the answer, (should be 'yes, we do - supernovas').

Look all control gear now being sold should be ok with both, just ask the supplier of what ever light you want to buy before you get it if it is ok. But keep in mind what I said about phillips HPI-T type bulbs.

£180 thats alot better then HH.

http://www.uk420.com/boards/index.php?act=...3f348829bfa4263

this show's the fastlight ballast that take's HPS / MH

must remember - USE THE SEARCH FUNCTION.
must remember - USE THE SEARCH FUNCTION.
must remember - USE THE SEARCH FUNCTION.
must remember - USE THE SEARCH FUNCTION.
must remember - USE THE SEARCH FUNCTION.
must remember - USE THE SEARCH FUNCTION.
must remember - USE THE SEARCH FUNCTION.
must remember - USE THE SEARCH FUNCTION.

Thanks for the link Oldpink! I will remember to ask about HQI-T Halides OT, (even if I occasionally forget about a search function every now and then )

answer back from Growell,

"Yes all of our light systems are compatible with either a son-t/grolux or
metal halide bulb - as long as it is of the same wattage rating.

Kind Regards"

pretty straight forward.

OK. I can now see that its possible to swap bulbs in compatible ballasts, thanks.

Next question - is it necessary to enclose MH bulbs, or can I use them in an open relector? I'm thinking of either :-

1 x 600W (Tayside Hydro's @ £60), or

2 x 400W (Osram HQI's from Holland Hydro @ £45/each).

The space will be 6' wide x 2' deep x 8' tall, probably ventilated using 2 x 6" RVK150A1's shifting 420m3h, one in (fitted with silencer), and one out (fitted with carbon filter - its important to me to ventilate odour as well as heat).

Just a thought Labrat.
If you are planning on using the same ballast and changing the bulbs. It may be easier to get 2 reflectors (depending on the price) and just unhook the reflector when you want to change. It will save you handling the bulbs.
I was thinking of doing this if i decide to get an MH.
It depends if you are planning on using the MH for part of flowering and veg or just for veg, as if you only need to change it once per crop, it may not be worth it.
I was going to give my ladies the MH over the weekend and the HPS throughout the week.


I'd reckon the choice of lights depends on how you chose to grow the plants. For a high number of small plants, i'd go for the 2 x 400W, but i thought you were intending on doing a low number of large plants so penetration is the issue and therefore, the 600W is the one to go for.
I dont know the spread of a 600W (anyone??) but i would guess it would be fine for your dimensions. I'm sure someone with a 600W will be along in a minute to tell me otherwise.



Wilbur

Its a thought Wilbur, and a good one.

At the risk of revealing yet more of my ignorance, I thought the reflectors were actually wired in. Correct me if I'm wrong, but are you saying that they are actually just loose hoods (complete with bulbs) which can be suspended from the ceiling and that the power is just plugged in, like the power cord on a PC?

As for 600W vs 400W - you're right, I'd prefer to grow fewer tall plants so a 600W offers better penetration, but I'm concerned that a single light placed parallel to the longest wall won't have the spread to reach the ends of the space. Rotate the plants?

Yeah, you would have to put a plug on each of the reflectors, but only have to wire in one power cable from the ballast. But it saves you getting your sticky fingerprints on the bulb and blowing it up.









Wilbur