Warren

LED's are current sensitive devices, not voltage sensitive. The intensity changes by altering the current through the LED. Different colours and types of LED have different forward state voltage drops. You need to know the forward state voltage drop and maximum continuous current rating of the LED before you can calculate the correct value potentiometer (rheostat). You'll also need a series resistor to limit the maximum current when the Pot (potentiometer) is wound to zero ohms. Stuff you need to know: 1. Forward voltage drop of the LED 2. Maximum Continuous Operating Current 3. Power Supply Voltage you're feeding it from Potentiometer: A variable resistor, usually with 3 terminals. With the pot shaft facing towards you and the 3 terminals facing downwards: The Center is the wiper. The right hand terminal is the side the resistance reduces when turned clockwise. The left hand terminal is the side the resistance increases when turned clockwise. We want the current to increase in the LED when the pot is turned clockwise so we use the center terminal and one on the right hand side (when the resistance reduces the current increases). Now the maths... V = Power Supply Voltage I= Maximum Led Current Vled = LED Forward State Voltage Drop N = Number of LED's in series R1 = Series Resistor Value R1 = (V - N*Vled) / I So if the PSU is 9V, 2 LED's with a forwards state voltage drop of 1.7V and maximum current of 20mA R1= (9-2*1.7) / 0.02 or 280 Ohms (use 270 Ohms as it's a readily available value). The pot value: The 280 ohm resistor sets the maximum current but we need to be able to reduce the current by increasing the total resistance in series with the LED's. To reduce the current and intensity to 1/10 of the maximum value you need a pot of 9 times the value (10-1) or 2520 Ohms to give you a total resistance of 10 times the original (the R1 value + the value of the pot). If you are going to put multiple LED's in parallel and want to dim them all at once: Calculate the resistor value R1 as before for the number of LED's you are putting in series. Each parallel string or single LED needs a R1 on it so when the pot is wound to zero ohms the correct current flows. The pot value will be the same as before divided by the number of LED strings. If 4 strings are paralleled then the pot is 630 Ohms. You now only need to check the power rating of the pot is high enough for the job. An approximate check is to take the maximum current you need, multiply it by 0.7, square it and multiply it by 0.3 x the pot value. So, for the 4 LED strings, the current is 20mA * 4 = 80mA and the pot is 630 Ohms. So the power in the pot worst case is 56mA^2 * 630 * 0.3 =0.056^2*189 =0.59 Watts So you'll need bigger than a 0.6W pot - in this case go for a 1 Watter... See the diagram attached:

Do you use this to filter the tap water or tank water? What type of filter is it - carbon, pleated cartridge, DI, RO? The only type of spa pool filters I've seen are pleated cartridge, - no good at filtering tap water...

Look at the specs for the Fuval to see how many l/hour it does. Get a pump with about 30% more l/hour. It's probably best placed near or in the tank on the Fluval inlet pipe. As I said in my last post, an Eheim would do the job really well (a bit more expensive but silent and it will go for years + it's ok in saltwater ).

Should be no problem as long as you add a booster pump to help the Fluval. It was designed to cope with the drag in only 2m of tubing, not 20m. A pump with a slightly bigger rating than the Fluval should do it. A small to medium Eheim would do the job well as it can run outside the tank (doesn't need to be water cooled).

Cool, see PM.

I know most of these people and they're good for it. If you do end up with any left over I'll gladly take one off your hands for the going rate...

Hi Kyle, RCD's aren't cheap but they're a really good safety device. You'll still get a shock if you touch something live but the RCD will cut-out so fast you'll hardly feel it and the duration of the shock will be short enough so you survive fine. Plug in RCD's (from a wholesaler) are about $74 (RRP) or $40.50 with a trade discount. You may be able to find a cheaper one at the Warehouse or Mitre 10 when they have a special. I have one on my heaters and lighting but not on the main pump. It's on a UPS so it runs 24/7 even when there's a powercut. Since it's a stainless steel pump and earthed, any fault in the pump should blow the fuse...

Redwood Aquatics had a very nice hex tank using halogens as the only light source. It was very nicely planted and had no algae. It beats me how they did it as I've only ever had success with very intense lighting... It does work and gives the tank a nice subdued light and it's obviously possible to grow plants too. Maybe you can contact them to see if there's any info they can give you about it.

It's usually best to get the minimum sized heater you can get away with. I use 2 x 300W heaters on a 1200L tank. One is set to 27'C and the other to 25.5'C. The 25.5'C one almost never comes on even in winter but the other one is usually on nearly all the time. This means if a heater fails to the more common on-mode there is less risk of your tank getting 'cooked' before you notice. If you then use two heaters of the minimum size you cover both ends, tank won't cook as badly as one big heater if it fails on and the tank won't get too cold if one fails to the off state. For 150L in a fairly well insulated house you should easily get away with 2 x 50W heaters.

Good on you Kyle, let us know what it cost. I hope it works well for you.

There's no ego trip on my part here. Who really cares what I know. The point here is to do with safety and dangerous advice. Hopefully you can see that. For your information however, a car ignition coil is not more dangerous the household power. If this is what you think then you are at great risk of getting hurt by the mains. A car coil only stores mJ of energy which it releases in about 500uS. It will give you a fairly big shock which you will feel and you'll probably jump a bit. Mains will not bite quite as hard but it won't let go. You'll get stuck on it until it burns out your muscles and nervous system because it's a continuous energy supply (unlike the coil). Then if you are still alive you'll end up with permanent damage and probably massive internal and external burns and scaring... So if you still want to risk your life messing with stuff you really aren't sure about go ahead, don't heed the advice people have tried to give you. mJ = millijoules uS = microseconds energy in the average car coil: L=2mH I=4A Joules = 1/2 LI² = 0.5*0.002*4² = 16mJ or not much at all. Energy from the mains: Say a body resistance of 10k ohms while in a shock-grip P=V²/R = 230²/10000 = 5.29J (or 330 times the energy in a car coil) The 5.29J per second is also sustained for the entire time the shock is received instead of a one-off 16mJ pulse... I'm not trying to make anyone look stupid here, far from it. I know about this stuff and just how dangerous it is. With electricity, a little knowledge is a dangerous thing. There is a lot to know about electricity and it's not simple. The purpose of the information above is to show there's more to it than you may think and to try to show you there's more you need to learn before delving into wiring your own mains devices. Small mistakes like thinking a car coil is more dangerous than the mains is the sort of thing that gets people into trouble. Please just listen to what I'm saying before getting hurt.

You may be correct about the 75% but then again most of the info here works pretty well for most people. We all have different setups and find different things work. The difference here is this information is about something that can be quite deadly to your health. Do you really want to risk killing yourself or other in your house to save a few bucks?

I'm not going to tell him so he can go fry himself. It's dangerous!! Snowman is only partly correct for DC (as there are many colours for DC voltage coding and no standard for extra-low-voltage DC wiring colours - did you know that?) but it only takes one very small mistake and poof... I'd rather he forked out double than get a phone call saying he's dead from dodgy information given to him from this site. People who know nothing about electricity know exactly that. They have no idea how to connect it and no idea about just how dangerous it is. Incorrectly wiring a fluro over water is a recepie for disaster. Incorrect information was given on this occasion. Had kylefish02 used that information it could have been very dangerous. It's basic common sense really. Bluetom, here you are giving information when you're not even sure if the box is called the ballast... You're in no position to give information if you are unsure yourself. As I previously stated, if you are at all unsure about what you are doing, leave it alone and get someone who knows to do it for you. I know the correct colours and wiring diagram as I have 20+ years experience in this industry. After thinking about it I decided not to post the information here as I don't want to be responsible for someone lese interpreting my information incorrectly and getting fried. You should consider the same thing, could you live with it?

Pegasus is right. You do not know what you are doing so leave it alone. Get someone who knows what to do (like a real electrician) to wire the unit up. They will also be able to make sure the guts of the fitting is safe. I cannot stress enough, leave this stuff alone if you don't know what you're doing. There is no 'rule of thumb' with electrical wiring, - there's the right way and the wrong way. Get it wrong and you're probably dead. Snowman obviously thinks he knows what he's doing but unfortunately isn't correct. If you have any doubt at all about what you are doing with electricity, do not touch it!!!!!!! In a modern house (with ELCB's) snowmans wiring would cause the ELCB's to trip all the time... If you wish to offer advice on this site, please make sure it's 100% accurate before posting. Edit - If you are not 100% sure about advice on electrical devices please do not post it.

Although you won't need metal halides for a local marine setup. That alone means you'll easily be able to afford a chiller. Good chillers start at around $600 so aren't a lot more than a couple of canister filters... It may seem like a big cost but it's still way cheaper than setting up and running a tropical reef tank...

For two weeks they should be fine. Your flatmates will probably overfeed the fish a bit anyway and this will help the plants a little as long as it's not too much overfeeding. You'll need to really stress not overfeeding to your flatmates as my experience has always been an overfed tank while you're away.

There's a company here in Napier called Classique Plastics with various sizes of acrylic pipe. I built my filter using 200 x 6mm pipe years ago. They have many sizes from 3mm upwards. They also make tanks, underwater viewing tubes (like Kelly Tarltons) and commercial skimmers. On a recent visit I stood inside a 2.4m diameter 6.5m tall skimmer for a 3.5 million litre aquarium in China. They've been a great resource for parts and advice over the years. The owners keep marines too, hence the help and support... They aren't too bad for price, - I made my filter housing for under $200 which included 1m 200mm tube, 1000 x 500 x 10mm acrylic sheet, 1m 50mm tube, 1m 25mm tube and 1 tube of acryfix glue. They also annealed all the bits for free once cut out and before gluing, - a critical step that stops everything cracking as the glue sets...

This matter is being handled outside the forums and there will be no further discussion.

Still working on it, - looks like we might get close to 500. A far cry from the 4200 species listsed and about 40% of the 1200 species allowed into the country now. Looks like we won't have as many fish in the future... Many thanks to everyone who has contributed. I know who you all are and the effort most of you put in, - it's been a very big job for some of you. It certainly won't go un appreciated... As I know who has contributed to the study, anyone I see complaining about the lack of fish species availalbe in the future who's not on my list is going to get stomped on very quickly. There's nothing worse than a hypocrite!!

Cheers!!!

As I stated earlier, for lighting (in general terms) this is not always true. Flurorescent lights and discharge lighting in general must be wired correctly for safety reasons. If the phase is connected to neutral and vice versa the insulation can be compromised or stressed long term. The most important part is any light with metal on it must be earthed. Basically, if you don't understand how the light works then you don't know what it's safety requirements are. This being the case, do not attempt to wire it up and get professional help. The FNZAS will not be responsible for anyone playing with electricity based off incorrect advice given in these forums. Wire stuff up at your own risk but we strongly recommend you don't touch it unless you know exactly what you are doing. This means understanding both safe working practices and operational theory of the equipment you are working on. I've worked in the electrical / electronics industry for 20+ years and have seen some very dodgy wiring done by people who didn't know what they were doing. It's only by good luck they are still here... I cannot stress these points strongly enough, - for your own safety, listen to what I've said.

:oops: Oops, Tuesday, thanks!!

I know, so here's the real facts: Any light with a metal frame MUST be earthed, so Lights definately DO have earths!! This is very important for safety. The phase should be wired to phase and not neutral. Neutral is at earth potential (if there's no wiring errors or no high earth leakage) and circuits are usually designed to keep the majority of the wiring at as close to earth voltage as possible. Wiring the phase to the neutral can often make all the wiring that used to be at safe potential live... It's common-sense really, - the more of the circuit that's at safe voltages, the less likely there is going to be a problem in the future. If you are at all unsure how to wire up electrical devices, don't. The combination of electricity and water we have in our hobby can very easily be lethal!!!

I have 116 forms total. I'm expecting quite a few from Kevin and I know of another 95 coming from someone else plus 75+ from some local people here. I have no idea how many Chris has. At this stage I have no idea how many we'll get in total. There's been a lot of work done by a few people, - the usual way things are these days. Thanks to these few people we may have a future of sorts in fishkeeping. We're still going to be way short of the total number we need... There'll be a couple of late nights this week compiling the final results once I get all the forms in. Remember, Wednesday 15th Nov is the deadline. That's this Wednesday, three days from now... To all those people who've done nothing, thanks a lot, - you'd better not complain if the range of fish available is somewhat diminished in the future. I don't care what your excuse is, I don't beleive you haven't found an hour or two to help out over the last three months.