Warren

Watch out for Silica based sands - they can cause a lot of brown algae...

I'd expect Southland Sand and Gravel could supply it. Years ago I purchased about 1000kg of fine sand-like gravel for several tanks (one is the 8 foot tank you now have - about 500kg went into that). It cost only about $70 for 1000kg and $600 in freight to get it to Napier... Southland Sand and Gravel (Invercargill) have a very big range of graded sand and gravels - both size and colour graded. Maybe worth checking them out.

The Hawkes Bay Aquarium Society will be holding it's annual tank and pond crawl this Sunday 1st May. We'll be visiting several local members and one fish shop as we do the rounds. I hope to see all the locals there + visitors are welcome. Start time and place yet to be confirmed (most likey 1:00pm).

We had a rat once that chewed a hole through the floor to get inside at night and eat whatever it could find. You could hear it chewing the hole bigger every night... On night 4 I set a rat trap. Sure enough, within 5 minutes of the lights going out we heard it chewing. A few minutes later the trap went bang so I jump out of bed and ran down to the trap. Sitting beside the trap (not caught) was a very stunned looking rat which was too fuddled to notice I was right in front of it. It only took a split second to instinctively pick up the rat trap and bang the rat over the head with it - no more rat... It would seem rats are pretty tough and even though rat traps are pretty mean, really aren't up to immediately killing the rat. However, they're not tough enough to handle a good hand-controlled rat trap tap to the head.

The forum wasn't actually started by the FNZAS. It was first set up and hosted by a member of the Upper Hutt Aquarium Society - Cees Lensink back in 2001. The site very quickly gained popularity and after only a short period of time became too big for Cees to manage on his own. He started bringing other people he knew and trusted on-board to help manage the site. I don't remember when it happened (will be in the FNZAS archives) but Cees donated the 'Fishroom' as it was known at the time to the FNZAS. Around New Zealand there are a number of aquarium clubs. These clubs can affiliate to the Federation of New Zealand Aquatic Societies (FNZAS). It's the clubs around New Zealand that make up the FNZAS. There is no actual physically separate organisation as it's volunteer members from the clubs that make up the committee of the FNZAS and manage it's affairs. When you join a club affiliated to the FNZAS you automatically become a financial memebr of the FNZAS. We're also looking at setting up an affiliate membership system where people who don't belong to clubs can sponsor the FNZAS and become financial members. A lot of the information you're looking for can't be seen on the site at present. When is your assignment due? Your question has raised an issue I hadn't previously thought about. I think it's time a full history of the FNZAS website was added to the front-end of the site so new members can see what we are and how we came about. Maybe also some info about the FNZAS and it's history too... As you can see, I've been around for a while. I been associated directly with the FNZAS and it management for a long time (coming up 20 years) although it's nothing compared to some others here... I've been fairly seriously involved with the FNZAS website from almost the beginning and have had various roles throughout that time. As Zev said, we're currently working on the next upgrade, the first stage to be rolled out within the next 2 weeks... My current role is as a silent admin - no forum admin presence but programming and site support.

If your tank uses 120W of power you will need approx 1800W of solar panels to 100% supply the tank with power. This is because it's only light for half the day maximum. Also, in the morning and evening the sun is at an angle to the panels so efficiency is very low (less than 10%). As the sun moves throughout the day the efficiency improves to a maximum when it's perpendicular to the panel. The panel's rating of 120W is only for midday sun at the equator. Since we are a long way from the equator and the sunlight must pass through more atmosphere it loses some of its energy. In winter it can be quite cloudy, reducing the efficiency down to only 10%. Then you will need a battery that can store 120W of energy for about 18 hours (120J/s * 60 seconds * 60 Minutes *18 hours = 7.776M Joules) which at 80% charge / discharge efficiency works out to about a 180AH battery (for 100% discharge). Since only 50% max cyclic discharge is recommended to make the battery last a long time you will actually need 360AH. Then you will need an inverter to convert the 12VDC into 230VAC. Costs: Solar panels - 1800W @ $7.00/W = $12,600.00 Batteries - 4 x 100AH @ $400ec = $1,600.00 Inverter - 300W Sinewave = $700.00 This setup will take approximately 20 years to pay back compared to just buying power (assuming no maintenance will be required). Since the batteries need to be changed every 7-8 years and the inverter at least once the payback time can extend to well beyond 30 years... In other words, solar power is still just too expensive unless you are setting up a really big solar farm occupying several square km's. Wind power can be a good alternative but only if you can make the windmill yourself and only if you get a grid connected inverter so you can push extra power back into the grid. This also only works if you have an old style meter that will run backwards if you are generating. Most modern digital meters won't count down on negative power flow. Your power supplier will also have to allow you to generate as not many do yet in NZ. We are way backwards with our thinking - NZ is supposed to be a 'green' country but we're not very green in our attitude to home power generation yet. Even Australia is way ahead of use there and we certainly can't have that...

I've had silicone peel off the same way before as well. Yet, the same brand and part number of silicone worked fine for over 15 years on several other tanks I made. It's unlikely to be the builders fault. I never figured out why the silicone came off. I've always used the same method of cleaning and putting the tank together yet on a couple of occasions the silicone let go - maybe it's a batch issue??

Ok, before I mentioned the speed in South Korea. I'm now at my hotel in a small city called Bundang (pronounced 'Boondaang') - population 450,000. Here the internet is free and reasonably fast: I wish I had this at home in NZ...

Here's what I get from my hotel in Hong Kong at a jaw dropping $25 NZD per day!!!! It's very slow and insanely expensive for what it is...

12mm glass is ok on a tank 900mm tall if the tank is narrow as the side glass provides a high level of support. A tank up 800mm wide and 900mm tall has a safety factor of around 3.2 and if it's under 600mm wide the safety factor is over 4.4 It's about understanding where the forces are in the panel and how the other panels in the design support each other. Once the front panel width is as long as the height the support from the side panels rapidly diminishes...

The tank front glass is 2100mm x 900mm Actually, the safety factor of that tank when filled to the top is only 1.185 which is probably why it broke... Wouldn't touch it unless you only plan to fill it to 700mm or less. Even a safety factor of 2.2 on a tank this size is far too low. The add even says the front glass broke and had been repaired in Q&A section...

NZ is way behind parts of the world. I regularly travel to South Korea where they have one of the fastest internet speeds currently available. From the hotel I get 40-50Mbits and it's free! NZ hotels and ISP's need to wake up.

Fairly average for me. I often get near 19 on downloads. Airnet has their own racks in the exchange and doesn't share/piggy-back off the Telecom network. Therefore it's always stable and high speed... I never get below 14Mb.

Without any top bracing at all this tank would have a safety factor of 3.3 which is considerably higher that many currently available tanks (thanks to 10mm glass). With Euro barcing the tank would have a safety factor of 4.14 so about 25% stronger. With the bracing style it currently has it will be somewhere in between. If an end brace is removed the front to back panel of 600mm x 510mm will have a safety factor of 4 so will be fine. My only concern with removing an end brace would be the parallelogram stiffness of the tank. An earthquake would cause the top of the tank to try to twist itself off the base creating huge forces in the silicone. Euro bracing seriously stiffens the top of the tank and creates strong resistance to the parallelogram forces. Taking off the end brace and drilling a hole (or holes) for the filter pipes/wires then sticking it back on would be the best option in this case. The edge of the hole will need to be at least 20mm from the edge of the glass.

He may be a professional but does he calcualte the glass thickness required, go by gut-feel or just use experience? A tank this size with a safety factor of only 2.1 is a risk. If you are happy to take the risk, by all means go ahead. I certainly wouldn't build another tank under 3.8 safety factor. Make sure you get a warranty and be sure your insurance covers water damage in case the tank fails. It probably won't fail as there are many tanks built with dangerous safety factors that seem to last ok. I wonder how many tanks that broke in the Christchurch earthquake would have survived if their safety factor had been good... I've been asked by insurance companies before about claims made where aquariums had broken. In one case an aquarium had been made by a glass merchants who did no calculations and went just by gut feel. They made a 1200mm wide 900mm tall tank out of 6mm glass. When it broke at about 90% full they remade the tank out of 10mm glass. The tank lasted for 1 week after being installed and it broke as someone walked past it. It cracked diagonally down the front. It didn't do too much damage to their appartment but did damage the 2 appartments below quite badly. This tank had a safety factor of 1.64. There are many tanks around with safety factors less than this. The main reason they survive is because they are not very tall and usually quite small. Good luck.

What thickness is the glass you're planning to use? Here's some quick calcs from these pages: http://www.fnzas.org.nz/index.php?PG=glass2 http://www.fnzas.org.nz/index.php?PG=glass3 For a Safety Factor of: 3.8 = 15.85mm glass 2.5 = 12.85mm Safety Factor for thickness: 12mm = 2.1 safety factor 10mm = 1.5 safety factor Tanks this size are at extreme risk if the safety factor is under 2.5 As the tank length increases safety factor has to go up. For commercial situations the recommended minimum safety factor is 3.8 I'd also look at a double height bottom brace around the perimeter on the inside bottom of the tank. This puts the main structural joins in tension rather than shear where the silicone is very weak.

Eh - sound pretty normal for me. My brain (what little of it there is) always feels like mush...

It's likely the tank will be closer to 1000kg. All the weight adds up pretty quickly and gravel is very heavy. Even so, given it's length it should be fine. My only concern would be securing the tank so it doesn't move. High-rise buildings move much more up high than at ground level so they amplify the movement of earthquakes. I'd make sure the stand is well secured to the building and the tank is well secured to the stand. You don't get earthquakes - neither does Christchurch...

Without bracing this tank has a minimum safety factor of 3.63 and 1.7mm of deflection. With bracing it would have a minimum safety factor of 4.99 (137.5% stronger) and 0.23mm of deflection. The minimum recommended safety factor for any tank in commercial situations is 3.8. I'd say you'd be ok without bracing but much better off with it. The main thing to consider with unbraced tanks is earthquakes. An earthquake will create a lot of diagonal stresses on the tank. If there's no bracing it will significantly increase the corner stress on the silicone which in this case will be the waekest part of the tank and most likely to let go. Top bracing will help strengthen the top of the tank and reduce the diagonal stress significantly. For this reason alone I'd look at bracing it unless you plan to have the tank with an open top...

Yeah it's a very good TV - I'm just used to 4 x 18" subs (well, 2 x dual isobaric 4th order bandpass) with amazing response down to 15Hz so I wasn't too impressed by the bass from the TV. Given the bass driver is only about 100mm in diameter and less than 10mm thick, the TV does pretty well - at least it's sound is fairly clear... I went to Harvey Norman where they had most of the major brands of each size stacked close together connected to the same signal. The Samsung stood out significantly above the rest in colour and contrast - I like the glossy surface finish as well as it seems to give the picture extra depth.

If the correct amount of CO2 is added while the lights are on and the plants are pearling well the O2 content in the water will be saturated and O2 will actually be gassing-off at the surface. With the lights off the plants use O2 and generate CO2. If you're going to control the CO2, I wouldn't turn it back on until the same time as the lights go on as there will already be a good supply of CO2 - no need to turn it on 1 hour before the lights. Others here have good success leaving the CO2 on 24/7 - I've never tried it but it obviously works. I never tried it because I set up a solenoid on the CO2 from day one and was too chicken to try leaving it on overnight - could have been a costly mistake. If you are worried about not enough O2 at night you could always turn on airation when the lights are off...

Good TV - I've got one of these too. The Sony has a more natural picture with normal settings - ie; pictures of trees and grass look more natural. The Samsung on normal settings tends to overblow the colours somewhat on nature but looks amazing overall. However, after messing with the settings for a while it looks pretty good on nature shots now and the contrast is still much better than the Sony overall. The sound is rubbish though - only ok if you put your sound through home theater.

That's good - my maths was about right. One thing I forgot to mention in my last post was I turned off the CO2 at night so it was on for exactly 12 hours a day. Based off that usage and yours, you would get approx 60 days if turned off at night. Leaving the CO2 on 24/7 will double the already high cost of running this system...

Does the tank wobble on the box its sitting on? Give the tank a good push where it meets the stand. If there's any movement at all from the force you can put on it then it may let go in an earthquake. There's also no rim around the top of the box so the tank can slide off - this would be my major concern.

+2 Discus are fine with CO2. I did turn mine off at night but only because I ran a KH of about 2 and didn't want to risk pH crash overnight. The CO2 was on a timer with the lights. I never tried leaving the CO2 on and monitoring it to see what happened as it was pretty simple to add a solenoid to the CO2 outlet.