Warren

Thanks Alanmin, This is pretty much what I was expecting. With the temperature difference you're seeing it is nothing to worry about. It's less than 10'C so it will be ok. Standard float glass will break if the temperature difference is 55'C and that's without any other stress from the water pressure. This would only occur if a certain point on the glass bottom had very good insulation and the rest was well coupled to the water ie, 50mm substrate at one end of the tank and 300mm+ at the other. In that case it's possible to get a large temperature difference that will adversely effect the tank strength. If toughened glass is used for the bottom (like my tank - Ex BNZ Bank doors) then the temperature difference can be 250'C and this is impossible to get while there's still water in the tank. 10'C will be causing a little extra stress in the glass where it joins the front, back and sides but the silicone will stretch to sort this out. The extra stress will be minor... It is something to consider during tank design if bottom heating of the tank is going to be used and no undergravel filter will be installed. You may have to go up a few mm in glass thickness to compensate for the extra stress. Alternatively, get the bottom glass toughened.

Maybe the heater is not coming on at all. Mine hardly ever come on in summer...

Yeah, nylons work fine but beware of them falling apart when the Purigen is regenerated. Chlorine very quickly destroys the nylons and you may find you need to replace them every few regens. Also, as Purigen ages the size of the sphere slowly gets smaller. You may find some of the Purigen will eventually fit through the nylons. "The Bag" is made from something similar to nylon and it eventually gives up as well but you should get about 2 years out of one before it becomes too brittle and eventually bursts. "The Bag" is also much finer than nylons. I always give "The Bag' a good stress-test after each regen before putting it back into the filter. I'd rather it break open on the kitchen bench than inside the filter... I've used up at least 5 of "The Bag" over the last 10 years but I'm still using the original Purigen. It doesn't work as well as it used to but it still works well enough so I don't need to replace it yet. I once emailed Seachem to ask how long it lasts. The reply was "You'll know when it's no good anymore". Well, I've been waiting a long time and still don't know as it's still going strong...

That would be great - I'm interested in the effect the gravel has as an insulator... I think the biggest benefit of undergravel heating in planted tank is a very slow flow of water in the gravel due to the thermal currents. The idea is to add enough heating to create a flow that keeps the substrate fresh but not enough to wash the rich supply of nutrients out into the tank water. The only difference I've noticed in the past is tanks with undergravel heating do not get the gas bubbles forming in the substrate that often occur in non-undergravel heated tanks. If you put a rich substrate containing any trace of organic matter under the gravel to feed the plants it will rot if there is no flow. After many years of operation small organic particles seep into the gravel. These also rot if there is no minute flow to spread the nutrients to where the plant roots can use them. Well, they will rot anyway but the difference is hydrogen sulphide gas bubbles or not...

I used carburetor jet valves for mine (idle jet). Went to the auto wreckers and searched through their part carbs (the ones that are damaged) to find a suitable needle. I made the body out of brass. The hardest part was finding a tap that matched the very fine thread on the carb needle. Blackwoods Paykels got one for me and I did the rest using a drill press and a piece of hex brass rod. The inlet and outlet tubes were short pieces of 4mm copper tube I had lying around and were soldered to the brass body. The only tricky part was getting the O-ring to sit into a grove to seal the thread to the body. It took about 30 minutes to make but over 3 hours to find the parts. Look at what your time is worth to you or how much you really fancy making your own one. May be better off buying one from Hollywoods...

Can you measure the temp at the bottom of the gravel just as the heater turns off. Would be interested to know the temp different between the water and bottom glass... I'd say you get away with it due to only 50mm depth of sand. If you had 200mm or more like many planted tanks you would have problems. The biggest issue comes with differing thickness of gravel creating different temperatures in different areas on the bottom glass. This adds extra stress to the glass and more risk of breakage. If the temperature difference is big enough the glass will break.

If you have an undergravel filter a heatpad works sweet as there's water flow to draw the heat away. If you don't have an undergravel filter and want to grow plants then you can't have all your heating from a heatpad under the tank as the base of the tank will get too hot by the time the heat transfers through to the water. The gravel acts as a fairly good insulator. Not only will the plant roots get too hot but you'll risk breaking the bottom glass. It's common practice on planted tanks to have 5-10% of the heating from below with a normal heater providing 90-95%. I've used a thermostat to control both the undergravel heating and tank heater. The heater was set to max temp so it was on all the time and the thermostat controlled the power to it. On my current tank, I used 25mm poly under it so there's almost no temperature drop between the water and bottom of the gravel. Worst case the temperature is 3'C lower where the gravel is approx 200mm deep. I'm wishing I used about 5% undergravel heating though as there is not much flow in the gravel leading to the odd stale spot...

Alan, undergravel heating works a treat on planted tanks. It help keep the substrate fresh but creating water micro currents and stops the plants getting cold feet if there's a cold snap.

Well, I can say for sure it's not a rip-off. I purchased 500g of Purigen 10 years ago on a trip to Australia. It wasn't available then in New Zealand. A year later I imported another 250g as I was so impressed by it. If it is currently $60 + $30 for "The Bag", it is still a bargain. The alternative is Activated Carbon. Purigen, total cost = $90 (can be regenerated). Activated Carbon, cost $10 (for an equivalent amount - cannot be regenerated) Cost to regenerate Purigen. Budget Bleach = $2.00, half a bottle required = $1.00. Sodium Thiosulphate, 20g (25kg = $75.00 so $74/25000*20) = $0.06 Replacing Activated Carbon every month = $120 / year Regenerating Purigen every month = $12.72 / year So with the initial purchase price of $90 + $12.76 it's still cheaper to use Purigen. After that you save over $100 a year. I find Purigen works better than Activated Carbon as well. The water gets very polished very quickly. Nitrate is the end-product of the biological cycle so Purigen does not harm it. Plants need very little Nitrate and prefer Ammonium as it's a much simpler nitrogen compound. Algae like Nitrate however so it's best if it's kept to a fairly low lever (5-10ppm).

If you can't get the lights at wholesale then the LFS is often similar price so may as well go with a good daylight tube from them. T5's in the colour range you'll be looking for are a bit harder to find at wholesalers but not impossible.

Try Mastertrade, Stewarts, Rexel, Ideal Electrical or any good lighting shop. Unless you know someone in the electrical trade they'll likely charge you retail.

Yeah, I'd go with sharn, hex is much more likely than flukes based off the info you've given. If you find it is Hex, here's what to do. Treatment with met: For oral treatment; add 250mg of powdered met to 100g of food. Crush the standard tables into a powder and mix into food like beef-heart or thawed discus tucker. Feed twice daily for six consecutive days. For tank treatment; add 1000mg per 100L of water. Crush the tablets and dissolve in 1L of lukewarm water. Slowly add to the tank by evenly distributing over the entire tank surface. Raise the tank temperature by 3'C. Treat for 3 days followed by at least 30% water change and add activated carbon to remove the remainder of the medication. Return the tank to normal temperature. After five days, repeat the treatment. Make sure there is nor activated carbon or other form of adsorption material in the filter during the two treatment periods of 3 days. Use new activated carbon for the cleanup of the second treatment. Warning: Metronidazole has been successfully used for many years but it can have negative side effects and in rare cases can kill the fish. If any negative side effects are noticed, treatment should be stopped immediately. Met is a prescription drug so you'll need a Vet to get it for you. It's not expensive but you'll need to find a friendly vet who doesn't charge too much.

If your discus has gill flukes it will be pumping its gills much faster than normal. If it's not rubbing itself against things and not effectively 'breathing faster than normal' then it probably doesn't have flukes. Discus are quite prone to them and they can come in with other fish or some foods but they're still quite rare. I've been keeping discus for over 10 years and only had a case of flukes once...

Compared to: Product Description: MASTER TL-D REFLEX 36W/865 SLV/25 Commercial Code: TLD36W865REFLEX Bulb Shape T8 Bulb Finish CLEAR Watt (W) 36 Volt (V) 220 Cap Base G13 Color Temperature (K) 6500 Lumen (Lm) 3350.0 Beam Angle (o) - Line Frequency (Hz) 50 Color Rendering Index (Ra) 85 Color Descriptions 865 COOL DAYLIGHT Average Life Hours - As richms said though, they're lower lumens/W so you'll need more...

The datasheets for the TLD96 state they're colour 98, not 90.5 They are quite superior to the TLD86. I've used both and set side by side it's easy to see the difference. It's like the difference between a 3 and 5 phosphor tube. Product Description: TL-D 90 GRAPHICA PRO 36W/965 SLV/10 Commercial Code: TLD36W965 Bulb Shape T8 Bulb Finish - Watt (W) 36 Volt (V) - Cap Base - Color Temperature (K) 6500 Lumen (Lm) 2100.0 Beam Angle (o) - Line Frequency (Hz) - Color Rendering Index (Ra) 98 Color Descriptions 965 COOL DAYLIGHT Average Life Hours -

There's at least two type of 6500K tube available. One is colour 86 and the other colour 96. The 96 has much better colour rendering but is about twice the price. Plants also grow a bit better with the 96's as well.

As someone else mentioned here recently, it's not the K rating that's most important, it's the colour rendering index (CRI). Natural equatorial midday sunlight has a CRI of 100. So the closer you get to this, the more natural the fish colours (and plant colours) will be. For fluro's, about the closest you'll get is colour 96 from Philips or Sylvania TLD96 series lamps. They have a K rating of 6500 and a very natural look. They do not artificially enhance the reds or blues like some other lamps. It really comes down to the look you want and that's entirely personal preference. For plants, go for 6500K colour 96 lamps. 14000K will make things pink and enhance the reds and blues but will not look natural but have a nice effect (that's what happens when you mix red and blue - you get pink). Typically the higher the K the more blue it gets. Watch out the high K lamps - they tend to cause algae in freshwater tanks.

Pays to price around. It's not difficult to find different retail outlets with massively different prices.

Hmm... Spot the people with MTS eh

I don't think anyone has money to throw round much... I hope it works out for you one way or another.

Nothing to feel stupid about. We've probably all done similar things before. I call it learning. 8)

Bummer!! Did you pick it up or get it delivered? It's always a good idea to check what you are buying. I used to get caught regularly for not checking things to find they weren't what was advertised or worse still, - broken. I now check everything I can think of when picking something up. Doesn't mean I still don't get stung, I do have a rather limited think-box so I usually don't think of everything that needs to be checked... You could always return the tank as it's not what was advertised... The glass company will likely shorten the glass for you for nothing if you decide to keep the tank.

Yes, have built 2 tanks in Restaurants locally that are 750mm deep using fluro's with fish only. Look great but would look better with MH. They are 2400 x 700 x 750 with 6 x 58W and 6 x 18W on each tank. 2 x 250W MH would have worked similarly but may have been a bit brighter at the bottom. However, 3 x 250W MH would have been best. My guestimate would be 2 or 3 x 30W tubes for the tank in question. Start with 2 and if it's not enough add another one. If you can find a cheap 2nd hand MH fitting of 75-150W then it would likely be cheaper. They can be hard to find however. Having used both my preference is MH as it looks more natural.

If you go for fluro's, colour 96 is the best for natural colour rendering as it's about the closest to that of mid-day sun. Philips or Sylvania TLD96 series are great. For 750mm deep you'll be pushing it with fluro's but they will do it if you use an extra one or two.

Second-hand is a good cheap way to go but do be aware that different MH lamps can have different operating lamp voltage and may need a different ballast to the one you buy - especially if you want to change to a different brand bulb suitable for an aquarium. Most shop lamps are well below 6500K colour temp and will need to be replaced for use with marines corals.