Robert Smith

Culturing cockroaches is easy, just move to Sydney. And at certain times of the year you get plagues of flying white ants. The fish love them!

Isn't that supposed to be: "Obit anus, abit onus"

The only reason to use acrylic is if you need odd shapes. If you want scratch resistant (and strong) use polycarbonate, but that costs a bundle! I almost choked when I saw sheets at Bunnings for about $80 (1.2x0.8mx6mm or thereabouts). Oil crisis, what oil crisis? It costs $3.50 a litre for water. they can get oil out of a 1km deep hole, ship it across the world, process it into petrol and sell it for <$2. And that includes a bunch of tax! I want the world to get upset about the water crisis! It takes about 2kg of oil for every 1kg of plastic. About 25% of oil becomes petrol. A "barrel" is 159L. The specific density of oil is about 0.9 g/cm3. US$100 a barrel (spot-price, so probably a gross over-estimation). 1kg of plastic = US$1.40 worth of oil or $5.60 worth of petrol. That sheet of polycarbonate (density 1.2g/cm3) weighs about 5.8kg so contains about $8 worth of oil. A ten times increase due to processing and mark-up! That's more outrageous than the cost of water!

Warren's right, your problem should not be heater response time or linearity of response or really anything about the heater (presuming you spent more than about $0.17 on your control circuit). The problem is sensor feedback (control loops) and they are notoriously dependent on the environment. A large thermal mass like a tank of water can be a very good thing for control loops, it acts as a buffer. eg1. Having a large still mass of water with a sensor on the far side of the tank gets you nice predictable heater response, but massive overshoot in tank temperature because it take a long time for the control loop to respond. But you don't get undershoot because heat loss is (mostly) uniform (wheras the heat source is a point). eg2. Having the sensor too close to the heater means you get no under/overshoot, but the heater will be going beserk trying to keep up with the minor fluctuations caused by the changing conditions at the sensor. The best situation is having the sensor far away from the heater, but having a very well mixed tank so the sensor sees changes quickly, but those changes are representative of the whole tank, not just a small patch of water or a particular current. So have a well mixed tank, keep the sensor out of the filter current and not close to the heater I think the control loop involving the environmental effects will massively overwhelm any hardware issues.

This has the makings of a great YouTube video! By the way Spider, are you sure you're a boy? ("read the manual"!) That's almost as funny as the Yellows getting yellower.

Instead of trying to pull it off, try pushing it off. Begin by closing one tap. Wear a pair of rubber-soled shoes and grip the bottom of the filter with your feet while pulling upwards with your hands. Now take a deep breath and blow really hard into the other tap. If you start seeing stars then stop. I've never tried this myself, but then who would! Even if this doesn't work, it should make your yellows piss themselves!

By the way, if you are using Danish oil, the more coats the better the finish. The first few are diluted (wipe-on, wipe-off) and using steel wool in between. If you are diligent you can get a phenominal finish. I've never seen better than the finish I have on an NZ heart rimu TV cabinet I made. It has about 10 Coats of danish oil and looks and feels like silky glass. More depth also gives you more protection.

Hi Cowboy, I have an 80L tank with glass cover (with a 4 cm gap down one short edge to allow tubes etc in/out). I used pine with Danish oil. I can't remember how many coats, but I typically would put down at least three and I think this was done in a hurry, so it's probably three coats. It looks a bit like Dwalk's, but the wood may be thicker on mine. I get condensation on the inside over the 4cm gap in the glass and had to add a line of silicon to act as a dam/drip-line to stop the condensation running out the sloping lid. I've had no substantial warping although I do get some mould growing on the inside of the lid. Most of it wipes off, but over the last two years some has grown into the wood. The outside still looks excellent. Danish oil may not be the best, but it seems to do the job well enough. Bob

With a level you are measuring whether the metal is "level", and if the floor is not level, or the legs are not even then you can get the wrong result. With 8 legs you make the chance of one leg being the cause of being out of level much higher. what you need to measure is whether the tank support is planar. If you have a piece of plywood or other planar material (like the base of the glass tank) then drop that on top and see if it touches all the supports without bowing. If yes, call it planar and drop your tank on top and verify it sits evenly. Then you can block up any legs that you need to to ensure the tank is level (ie. not on an angle, as opposed to twisted/warped) so that the water doesn't all pool down one end (which, by the way may be easier and faster than using a level to align then tank, just drop a litre or two of water in the bottom and watch where it pools).

Ditto. And that only gets worse because you have eight legs. You can prove it to be warped/not warped using a level and a ruler and assuming your floor is a flat (but not necessairly level) plane, but it's unlikely to be reliable enough.

A level cannot tell you that the stand is twisted unless it is a very long and very straight one, in which case you're using it as a straight-edge, not a level. If you're using the 'level' part of it then you cannot be sure. If it's a good level then the straight-edge might be long enough to show any warping of the top pieces of metal, but even then I suspect not. I think the suggestion to carefully place the empty tank on top is the best. That will tell you if the frame is warped. If it's not then you just pack out the legs. Some people say measure three times and cut once, others say measure once carefully then cut once carefully. Me, I typically measure three times and usually end up cutting three times anyway. Knowing my limitations, I only ever make tripods. The benefit of this is that all our furniture fits nicely into the corners of the rooms. The downside is that this includes the dining room table and all our chairs (stools), but thank God for corner baths and flat screen TVs!

So what's the point of UV filters?

I get green spot algae in the winter when the sun is low and reflects off the windows of the building next door and onto one corner of my tank. Ira, doesn't green spot spread through spores? So a UV filter should also reduce the amount of spores in the tank.

I use a 3M "non-scratch" scourer on those hard to remove algae spots. Its scourer surface is green and like rough rubber. I've been using these for about 2 years and have started to notice some fine scratches. This may just be unseen grit getting trapped in the sponge, but I am careful and maybe it just indicates there's no avoiding scratches if you use scourers.

Soap and water is always a good start. Do not use scourer pads or any abrasives. You often don't see the damage until the perspex drys out. However, to contradict myself, you can use some very fine abrasives on perspex to remove fine scratches. Brasso with a rag is good for this. Just ensure the surface is very well washed afterwards, Brasso is not exactly healthy!

The measurement technique is the best diagnosis. But if you've now got 50W of lights where you used to have 30W of light your tank is either a lot brighter or a lot hotter! You can answer the first question yourself. An extra 20W is quite a lot in terms of heat. I don't know the bulb in question, but some blue/white bulbs actually generate blue/white light and the blue colour on the outside of the bulb is not what makes the light look blue, it is a layer of plastic that absorbs the UV, preventing UV damage to fittings etc. If the light is obviously blue, then it's likely that the blue bulb is acting like Stella's cellophane. If the light is bright white then I think the blue is a UV filter.

The amount of heat you get depends on the efficiency of the bulb. This can vary quite a lot. For example, for 40W 4ft bulbs the amount of light can vary from as low as 1900 to as high as 3300 lumens. I've no idea as to the efficeincy of yours, but worst case is that you'd have a bulb that gives significantly less light and thus more heat. But just because the bulb has a blue filter, that doesn't mean it is less efficent than your previous bulb. Without the details of efficiency from a paper specification (lumens per watt) try measuring the temperature with a thermometer under the hood!

I had a similar leak appear at a seam at the base of the hose connection on my Sacem Pegasso, perhaps not as bad as yours, only a few mL a minute, but it adds up overnight. I 'temporarily' fixed it with a squirt and smear of transparent silicone. That was a year ago and it's still there and still doesn't leak.

Look out for noise!

Yeah! Keep going. People like this give me the s@#ts! Just stay calm and keep the paper coming and he may start to realise that the easiest approach is not yell until you go away, but give you what you want. It takes a special type of personality to do this well and that's not usually a compliment, but the world needs you (us) Language Removed... Mod Bill... . It's your social duty!

Some reference data: For 40W tubes Lamp Color : Color Temperature : Minimum Acceptable Lumens : Best Available Lumens Warm White : 3,000K to 3,500K : 2,880 : 3,300 Cool White : 4,100K to 4,200K : 2,880 : 3,300 Full Spectrum : 4,800K to 5,500K : 2,950 : 3,250 Daylight : 6,000K to 7,000K : 2,000 : 2,180 I've seen GroLux rated at 6500K, but... I've also read that Kelvin rating can be misleading for fluorescent tubes because they emit in narrow spikes of light rather than broad intensity. The Kelvin rating is only reliable for what the human eye perceives, not what plants receive. Perhaps this is why Sylvania don't list a Kelvin rating.

You're right of course Alan, but the concept is still an improvement over the existing 2W/Gal rule (assuming that this actually a rule people use!) I would assume that the 2W/Gal rule takes into account efficiency. But of what kind of light? Metal Halide or Fluro? Does anyone know? My data based on sunlight does not take into account efficiency. It appears the numbers may be on the high side, because if you assume a fluoro is 10% efficient (ie. this is the amount of energy converted to light, and it ranges from about 6 to 15%) then you'd need 8000W of fluorescents to get 800W of incident light for an equatorial tank. 8000W seems excessive! I should probably be usinf Lumens anyway.

Replying to yourself is not a good sign, but I realised I'd better put up my own tank numbers. I have 50W of ultra-white tungsten halide (3500K) in a 450l x 350w x 450d tropical tank. This is: 50W x 0.45m / 0.16m2 = 140 W.m/m2 My lighting setup is a bit wierd and definitely under-powered, but according to my own calcs I should have about four times the lighting, or about 200W of lights.

After some discussions about lighting I took Vinson's numbers and resulted in a defining moment of fish keeping. I've invented the "Smithon" and even defined it. Behold! 1) Using 2W/Gal at 700mm and 3.78L/Gal I get 370W/m2. My working is: 2W/Gal = 2W/3.78L = 2W/3780cm3 For a 700mm deep tank, thats: 2W/3780cm3/700mm = 2W/3780cm3/70cm = 2W/54cm2 = 1W/27cm2 = 370W/m2 2) If we then assume that you can also scale the depth factor to get a universally scalable number in W.m/m2 (Watt metres per square meter): 370W/m2 at 700mm is 370W x 0.7m / m2 = 530 W.m/m2 I think the first constant (370W/m2) is safe to use because that is a linear factor, ie. more area equals more required light. The second constant (530W.m/m2) may not be because light penetration is not linear and different wavelengths of light penetrate water differently. A 70cm deep tank seems like a good compromise depth to me. Using this constant on a deeper tank runs the risk of pumping too much energy into the surface, perhaps causing evaporation and frying any surface dwelling fish. As a reality check: - A maximum of about 1000W/m2 reach the equator, but this typicaly averages about 800W, given clouds, dust etc.; - In the USA the average ranges from about 125 to 375 W/m2 per year. This includes nights, clouds etc. So assuming 10 hours of darkeness and multiply that by 1.7 to get the daytime average I get about 200 to 640 W/m2; So, I don't think 530W.m/m2 would cause any problems and could in fact be increased. If you kept equatorial fish it seems you could possibly pump out 800W/m2 and not expect any downside for the surface dwelling bodies. So if I assume the deepest tank will be 1m, this gives a constant of 800W.m/m2, which is about 50% higher than the 2W/Gal number you had above. So, I've officially created a new constant for fish keeping, the "Smithon" with units of Watt metres per square metre (W.m/m2). Tank Type - Max Lighting (W.m/m2) ----------------------------------------- Equatorial - 800 Tropical - 600 Temperate - 400 High/Low - 200 Do these numbers seem sensible to people with real-world experiance?

Vinnie, You're quite right, the W/L (watts per litre) guide is not good enough! We need a W/m2/m standard (Watts per square metre of surface area per metre of depth). The caveat will be a maximum W/m2, otherwise any fish that surfaced in a 1m deep tank may find her eyeballs fried in her head. Can anyone give us the dimensions of the tanks where the !/L guide comes from? It should be easy enough to covert from there. How much is too much? Bob