Matthew C Good : Musician, Software Engineer, Hobbyist.

Projects Posts

FishApp Update – It’s Doing Stuff

It looks like the FishApp is already providing me with some really neat and useful insights into my aquarium.  I recently added the ability to overlay and toggle multiple series on the graphs it displays, to make it easy to see if one parameter has an effect on another.  Take a look at this snapshot I took today:

Water age & nitrate levels over time

Water age & nitrate levels over time

This chart shows the average age (in days) of the water in my tank compared with the levels of Nitrate I measure using an aquarium test kit.  I compute the water age using information I record about water changes I do to my tank (a more detailed explanation can be found in the original FishApp post), and Nitrate is a mildly-bad chemical the can build up in your tank over time.  It’s the end-product of the Nitrogen Cycle in most fish tanks, and can only be removed by water changes or chemical absorption (which some plants and special filter media can do).

At least that’s the theory.  What this chart is showing me is that the theory seems to actually work out in practice, and that my tests are precise enough to actually be useful – always a good thing.  Even though I only have five data points for the nitrate series (because I don’t always test as much as I should), it is easy to see the nitrate curve following the water age curve.  They actually track pretty well, I think. You can see an ugly spike in the water age when I wasn’t paying enough attention to the tank, and the resulting high nitrate levels, which backed down after a series of regular water changes.  When the water age started creeping back up again, so did Nitrate levels, and then both went down again after we moved from Tennessee to North Carolina (and changed out about 2/3 of the tank water for fresh in the process).  Very cool.

Since nitrate is the last state that fish poo reaches in the nitrogen cycle, it would not surprise me if there were a delay between water age and its effects on nitrate levels.  I don’t really have the data to support that right now, but I will try to be more diligent in my testing, and perhaps we can figure that out soon.

If there are any aquarium owners out there who are interested in the FishApp, you can sign up free and track your own fish tank in a similar fashion.  Here’s a link to sign up.

Naughty Rams, Caught on Video!

Caught my German Blue Rams spawning:

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Check out what happens when one of the Cory’s gets too close. They are so oblivious to their surroundings sometimes… We had heard horror stories about Rams getting aggressive when mating and corys losing their eyes… Luckily none of that here.
I also got some stills.

Building the A12 Microphone Preamp

Lately I’ve really been in the mood to build things. So I was very happy when I finally got some cash lined up and plunked down for the really nice-looking Seventh Circle Audio A12 preamp kit. My audio/recording friends will know why this is such a big deal, but for the others, it’s a thingy that makes mics sound better. And its way cheaper than many of the alternatives. But the real beauty of this particular kit is that you can mix and match eight different channels of several different “sounds” in one box. So it’s got lots of room to grow. Check out their full line of preamps at
Here’s a basic walkthrough of what I did to get my preamp running.
When you get the kit and break through the really great job they did packing the thing, you find yourself with a chassis & power supply prebuilt, and then a circuit board, some bags of parts, and a schematic.

So you have this blank circuit board in front of you and it’s a little daunting. There are a lot of holes and many of them are tiny and close together. Luckily, you have just bought a nice soldering iron and some helping hands, so you shouldn’t worry too much. Download the assembly instructions pdf and get going.

Be sure your work area is well-let, and start stuffing the components. Follow all directions carefully, look up what you don’t fully understand, and double-check each resistor with a DMM. I just have a cheapy $10 DMM i got at Sears, but it was enough to complete the project with relative ease.

Remember to trim the leads on the back a little. It will make working with the board easier. I used a nail clippers to do this, I’m not sure what you’re supposed to use…

Before long, it will start looking like something:

The kit uses high-quality Cinemag transformers, which should make EVERYONE happy. Audio guys sometimes underestimate the amount of coloration that comes from big iron transformers, and just call everything that’s colored “tube.”

Before long, the board is fully-populated.

Before you go plugging anything in, be sure to follow the instructions carefully and test as much as you can. I did fully re-check all the resistor color codes and cap values, as it said. It took a while, but you can smoke components if something is wrong. And that’s a hassle, I’d imagine.
At about this time you realize that there’s a few things you need to do with the power supply too, like attaching the ground wire (VERY IMPORTANT), and soldering up the lamp and power switch. My only gripe out of the whole project came here, because the PDF of instructions for the power supply appears to be for a previous revision where you had to do more of the wiring yourself. Now, they ship with a wiring harness. This normally would make your life a lot easier (and probably still does), but the instructions are vague on what you need to do and what you can skip. Also, the freakin’ little metal things you crimp on the wires to get into the white connectors are REALLY hard to get on solid. I suggest soldering them all after you crimp them, to be safe.
Now all that’s left to do is power up, do more testing with your DMM, and then calibrate the voltages with your DMM. Note that at no point should the bottom of the board or any of its electrical contacts touch the case or anything. This could create a short and I think bad things would happen. Note the bubble wrap:

You’re supposed to connect the leads to the op amp at one point here, and it is a little tricky. Some notes: You NEED both alligator clips and probes for your DMM. Mine just had probes, so I bought a cheap bag of alligator clip jumpers to attach, and that worked fine. It just looked funny. Also, you might wonder how you’re supposed to get the clips on the op amp leads while the op amp is still in the socket – well, the simple answer (for me) was to clip them on to the back of the board, attaching them to the big metal post things the op amp pins go into. Hope that makes sense. You’ll figure it out either way, I’m sure.
Wahoo! Stick it in its case, plug a mic, power it up, and YOU’VE GOT YOURSELF AN AWESOME PREAMP!

Hope that’s been enlightening. I hope to do more of these photoblog type things for more projects in the near future.

More Tetras

Kristin and I were finally able to track down more tetras on the other side of the city tonight, so after getting lost and turning around several times, we finally cleaned out the cardinal tetra stock at the 2nd petsmart in nashville. Now there are none in like a 30 mile radius. jeeeezz they are hard to find sometimes. But they are cool little suckers.

Fish are very sensitive to their water conditions, and these fish are kinda sensitive in particular. Sudden changes in things like ph, chemical composition, temperature, hardness, and cleanliness can stress fish out, even if its a change “for the better.” So its best to slowly adjust the fish to their new water.

The most commonly-suggested way to do this is to float the bag that the fish come in at the top of your aquarium for about 15 minutes and then add the fish. The theory here is that the temperatures will be equalized and that is the most important part. That may be true, but it is a much less than perfect method. The water can be heated by the florescent lamps and this method does nothing to adjust for chemical differences which can really freak fish out. If they aren’t used to the water chemically, they can have a hard time breathing (through their gills, ya know?) and that’s not good for anybody.

We did this last time with our cardinal tetras and the fish had a rough time making the transition. A couple of them actually were belly-up for a few seconds before they came to. Not what you like to see.
We found a better way of doing it. You put the fish in a small quarantine container and slowly take out some of the old water and replace it with the new water. Badda-bing, badda-boom, your fish are a WHOLE LOT LESS FREAKED when you add em.

After we added the new guys, they immediately started schooling with the old guys. They’re super-cute. There’s one guy, we call him “Lemon,” he’s the littles of the bunch and when we added him, his dorsal was clamped down a bit, and he had like no red or blue/green color – he was all pale yellow. In like three minutes though, he started getting some color back and perking up. He’ll always be little Lemon, though.
Oh, and here’s some more pictures of the corys feeding.

See the one in the front here?

That one’s ol’ blackeyes. Or blackie. He seems to be the smartest, least psycho of the bunch. All the other corys will be freaking out, swimming up and down the side of the tank, and blackie will be eating excess food off the log. Good ol’ blackeyes. What a good fish

That’s all I got for now. The [submersible] fish cam will be coming soon[-ish].

New Fish – Corys

We added four more fish to our tank… slowly, we’ll have it fully stocked. The four new guys are cute little Corydoras (C.trilineatus). They are little catfish-like schooling dudes that come from peru and ecuador. Here’s what one looks like:
Cory close up
The pet store had them incorrectly labeled as Corydoras Julli, but they are apparently commonly mislabled this way. When we first put them in, for the first few days, all they did was swim up and down and up and down along the right side of the tank, like a dog chasing its tail. They were acting all crazy.
They’ve calmed down a bit now, and spend most of their time looking for food along the bottom, or on the driftwood, or on plants.
They scurry about very cutely. And when they get spooked (which happens easily, sensitive little dudes), they kinda play dead.. they just go real still along the bottom of the tank and wait it out for a bit. kinda neat i guess.
all four corys hanging out
Anyway, for those of you who are actually nice enough to have read this far, i’ve got a little treat for you, i think. Assuming it works, I’ve posted a video of me feeding our tetras. They zip and zoop like crazies when there’s food in the water… its pretty cool. Check it out.

Fish Tank

[WARNING: If you’re not interested in reading a sorta long and maybe boring story about how kristin and I set up a fish tank, you may want to skip to the bottom of the post to see some neat pictures. If you remain undaunted, you may proceed…]
Kristin and I decided we needed a pet – but a really low-maintenance one. My dad has a fish tank with two beautiful discus in it and when we were home, we always liked to look at the fish happily, gracefully swimming around. So – we decided fish were for us.
There are a number of reasons for this. Next time kristin and I decided to randomly leave for a week or so, the fish may not even need food, and if they do, there are automatic feeders. Kristin and I are also Zoo Nerds (we’re members of the Nashville Zoo and hang out there now and then. We also have buddies in our cubbies), and like learning about the natural world. I’m sort of a science geek. So a fish tank (which is more-or-less a small ecosystem) is an interesting thing to learn about. It’s not as simple as just dumping fish in (see the nitrogen cycle, for instance), so its perfect for those of us who are still interested in a little science now and then.
We settled on a 55 gallon tank kit from Walmart. It’s actually a kit made by Marineland, a respected name, and just rebranded for Walmart. The kit included a filter, heater, thermometer, lid, lights, and some small packets of dechlorinator and food to get you started. Pretty nice kit.
Of course, take into account that water weighs somewhere in the neighborhood of 8 lbs per gallon… And you realize you’ve got to get a fairly heavy-duty stand for the sucker. So we bought a nice black stand. Another chunk of change.
Then I heard from my dad that I could get like 30% anything from this online store for a while, so I loaded up on supplies from them… We actually were able to score an upgraded filter, usually $70-$80, for $30. This was a good score.
We bought some books and read a ton on what fish go with what, what kind of water certain fish like, all about the nitrogen cycle, beneficial bacteria, planted aquariums, and the like… Ph, hardness, buffering, diseases, water changes, and the like. I like to thoroughly research my hobbies 🙂
We set it all up, put in a mixture of plain gravel and plant substrate (flourite) in the bottom, and bought some mopani wood (like driftwood, but does not decompose. a two-color dried african wood), and planted some aquarium plants (Amazon Swords and Java Ferns). We ran the sucker for a few days, and then it was time to get some FISH!!!
There were a couple options for us… We really liked my dad’s Discus fish, but we also read about this one particularly awesome kind of fish called Oscar Cichlids. They are cute in a very homey sort of way, with huge mouths and a mixture of drab and bright colors. They get to be over a foot long, and are very inteligent social animals. They recognize their owners, wagging their fins when you approach. If they get bored, they’ll tear apart the decorations in teh tank and rearrange them to their liking. Some of them even like to be petted. They can live to be 8 years old. They’re like a small dog – albeit one that has to be kept underwater all the time. We really kinda wanted one, but a 55 gallon tank was a little small for them (we couldn’t really put any other fish in it), and we will probably be moving at some point, perhaps selling our fish, and it would be hard to find someone willing to take such a large pet-like fish at the last minute. So we decided on discus. We’ll have an Oscar at some point, though…
Usually discus aren’t recommended for beginners. But my dad did it, and Kristin and I probably do a lot more research than most beginners, so we figured all would be well. We started to think of what kind of fish to stock with the discus. Turns out they really like to have schools of cardinal tetras around – it makes them feel relaxed. We decided to start stocking the tank with some of those. Petsmart only has four at a time, pretty much, so we bought them out. They are about an inch long, and grow to be up to two inches…. So these four tiny fish have this huge tank to themselves currently. Lucky little guys. We’ll be buying a few more tomorrow, to bump up the size of the school.
I’ve been doing water testing nearly every day to check for buildups of ammonia (to track the progress of the tank’s cycling) – but there is just not enough fish in the tank to register anything on my tests yet… However, somehow the ph jumped .4 after it got in the tank… The water is also cloudy, due to the fact that the substrate we used needs to be washed just ridiculously well (and we only washed it well). I think the two are related. The particulate in the water could be adding to whatever the ions are that make a high ph, and once i get the cloudiness down, with more water changes and gravel-vac’ing, the ph should come back down too. As the water comes out of the faucet, its 7, but the tank always reads 7.4-7.6 – this is pretty high for both discus and cardinal tetras – so something’s gotta come down sooner or later.
Without any further ado, here are some pictures!!
Fish tank, no fish.
Fish tank all set up, no fish yet. Note the cubbies at top left.
Cardinal Tetras by the Java Fern
A couple tetras, hanging out by the Java Fern. The Java Fern is currently tied to the mopani wood with string. The string will keep it in place until the roots take hold.
another shot of a Cardinal Tetra
Another shot of our cute little Cardinal Tetras. Soon there will be a whole school of these suckers in our tank.