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Old 05-18-2007, 06:59 AM   #4 (permalink)
fishstein
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Default Re: Help! Sudden Melting/burning Endcaps

I ran this question on another planted tank forum and this is what we've come up with so far:

tropicalfish
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Get some cooling fans first!!
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75 Gallon
Rena FilStar xP3, Aquarium Systems Visi-Therm 200W (2), Coralife 48" Aqualight 260W 6700K

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10 Gallon Hexagon
Hagen AquaClear 30, Visi-Therm Deluxe 50, DIY CF 20W 6500K CF, Hagen Natural CO2 System :: Bloodfin Tetra (1), Red-eye Tetra (3), Black Skirt Tetra (3), Harlequin Rasbora (6), Platy (1), Otocinclus Catfish (1) :: Rotala Indica, Hygrophila Difformis (Wisteria), Cabomba Carolina (Cabomba fanwort)
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Old Today, 12:16 AM #3 (permalink)
Fishstein
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The lack of a fan is not the cause - I've used these end caps and the same hood with 4 T8 48" bulbs for years without any problems. Does anyone have any other suggestions?

For all of the years I've run these end caps and ballasts except for the last 6 months, I've used them with 4 identical F32T8 48" Verilux full spectrum bulbs. $ of the same bulb.

A few months before the first end cap fried, I mixed an F36T8 Aquarelle with an F32T8 ADV850 on each of the two ballasts - perhaps running an unbalanced load on each is a problem.
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Old Today, 12:29 AM #4 (permalink)
phkhgh
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Fishstein,

Did you say whether you were using ODNO? If not, are the ballasts mag or electronic? If using ODNO, the caps like yours are covering part of the lamps, which get much hotter than w/ NO. Don't know how good an idea that'd be anyway.

Ballasts can & do go bad. I worked in maintenance during college & replaced a lot. Normally they don't cause probs when going bad, but...
Problems w/ any ballast, esp electronic, could be intermittent - but usually aren't. But I saw a lot that'd work ok for a few days, then act up, then normal again.

Unless you have equip to test current draw, etc., it might be better to replace ballasts. How did the metal connections in the endcaps look (before melt down), and how were the pins on lamps? Make sure all connections are clean, tight and not corroded.

Do you have glass between water & lights? If not, it's a good idea. Were both ballasts same brand / model? If they're mag, don't know how flexible those are for running diff wattage lamps at same time.
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Old Today, 12:47 AM #5 (permalink)
Fishstein
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** Thanks so much for the info. See ** below for answers

Fishstein,

Did you say whether you were using ODNO? If not, are the ballasts mag or electronic? If using ODNO, the caps like yours are covering part of the lamps, which get much hotter than w/ NO. Don't know how good an idea that'd be anyway.

** By ODNO, do you mean over-driven normal output? I don't know how to set that up. My ballasts are simply standard F32T8 electronic ballasts, each designed to handle 2 bulbs. Perhaps the ballasts can't handle the 36 W bulbs or can't handle balancing a 36 watt and a 32 watt on the same ballast. I'll also ask my local lighting wholesaler - I hope they know.

Ballasts can & do go bad. I worked in maintenance during college & replaced a lot. Normally they don't cause probs when going bad, but...
Problems w/ any ballast, esp electronic, could be intermittent - but usually aren't. But I saw a lot that'd work ok for a few days, then act up, then normal again.

Unless you have equip to test current draw, etc., it might be better to replace ballasts. How did the metal connections in the endcaps look (before melt down), and how were the pins on lamps? Make sure all connections are clean, tight and not corroded.

** There may have been some corrosion after so many years, especially since I don't keep glass between bulbs and water. I'll have to check. Is it possible that all I need to do is replace the old end caps that might have corrosion on the leads?

Do you have glass between water & lights? If not, it's a good idea. Were both ballasts same brand / model? If they're mag, don't know how flexible those are for running diff wattage lamps at same time.

** I don't keep glass between the water and the bulbs because it really reduces the quality of the light getting into the water, and my tank, while it's not super deep, is a 75 gallon 48" L by 18" W and 18" H, and with this setup, and the bulbs I have, I can get great growth without using more lights and more power by not using glass. A lot of aquarists I know recommend not using glass between the bulbs and the water. The bulbs are about 6 inches above the water and the hood is very well ventilated by cutouts on the back and top of the hood.
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Old Today, 04:26 AM #6 (permalink)
rich
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Quote:
Originally Posted by Fishstein View Post

Do you have glass between water & lights? If not, it's a good idea. Were both ballasts same brand / model? If they're mag, don't know how flexible those are for running diff wattage lamps at same time.

** I don't keep glass between the water and the bulbs because it really reduces the quality of the light getting into the water, and my tank, while it's not super deep, is a 75 gallon 48" L by 18" W and 18" H, and with this setup, and the bulbs I have, I can get great growth without using more lights and more power by not using glass. A lot of aquarists I know recommend not using glass between the bulbs and the water. The bulbs are about 6 inches above the water and the hood is very well ventilated by cutouts on the back and top of the hood.
I'm sorry to say, but your aquarist friends reccomendations are making your tank electrically unsafe for the sake of a tiny light loss. Using a shield is pretty much necessary in a closed hood. If you're going to suspend lights above an open tank with a good air space, it might be better. I'm not sure who would tell you to suspend a light 6 inches above the water with no shield. This very well could be the cause of your short circuit - one fish breaking the surface of the water or a particularly high evaporation cycle would be all it would take to douse a fluorescent endcap with water. If you're worried about light problems, you can make a shield out of acrylic or fused quartz as they interfere very little with the spectra, but you need something in there to isolate the electrical system from the water area.

-Rich
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Old Today, 09:16 AM #7 (permalink)
WibblyPig
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Did you have the little gaskets in place and are you using waterproof endcaps? If not, there may have been corrosion in the endcaps which caused arcing.
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Unread Today, 10:56 AM #8 (permalink)
Fishstein
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I'm using Coralife/Energy Savers water-resistant end caps (water-resistant, not waterproof). I am 99% sure the problem emanates from corrosion in the end caps.

I once dropped one of the end caps (when it was off) in the tank and though I let it dry for two days, that was the end cap that originally fried a few months later. As for the other end cap that fried, that was probably related to cumulative corrosion in the end cap over a period of 8 years. I think my best first bet is to replace the end caps with either new water-resistant end caps (I have enough spares to replace them all), or better yet, to replace them with fully waterproof end caps (just saw Ice Cap waterproof end caps for T8 here: http://www.aquariumplants.com/Ice_Ca...ir_p/ic738.htm ). Anyone know of any other waterproof end caps worth checking out?

Two things that I'd like to verify:

1) whether or not the ballasts can safely handle one 36 watt and one 32 watt on each ballast - in other words, can the dual F32 electronic ballasts handle the mixed wattage - everyone I asked in electronic stores when I bought them said yes. But I want to double check.

2) I have glass shields that go over the top of my aquarium water. However, they are very thick (about 1/4-1/3 inch glass) and do cut a lot of light, and are a real pain to keep clean and clear; they also keep the water temp higher and cut down on gas exchange to keep good oxygen in the water. What I might consider, if it was safe, is to use clear T8 tube covers the likes of which I have on my 48 in. F32 T8 Verilux full spectrum bulbs that I have in ceiling fixtures in my home office. These are clear tubes that cover the entire bulb and protect it from splashes, dust, etc. and protect people from a shattered bulb. The Question is whether these plastic sleeves, when used inside a hood (granted a hood with a lot of the back cut out for ventilation), keep too much heat around the bulb. Anyone ever use these clear plastic tube shields inside a hood?
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