Discussion in 'Turbo's Aquatics' started by Turbo's Aquatics, Aug 4, 2011.
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Yes, but it's a small chamber and there is a lot of flow through it.
Here are some pics of the canvas screen taken with my phone and with this cheapie kids' toy digital microscope
100x (brightness/contrast adjusted because the toy sucks)
Roughed up (with a wire brush drill bit and then a quick pass with a saw blade)
Mortar applied (fresh)
100x after 2-3 day curing, patted dry
You can see how the shredded canvas material is poking out all over the place, which gives you an indication of how thin the mortar later actually is. It's sacrificial anyways so you don't really need it to be thick, really you don't want/need it to be. Thanks again @Paul B for nailing this one on the head. The microscopically rough texture is the perfect medium for fast initial algae growth. The roughed-up plastic canvas screen takes over in the long term after the mortar releases. I've found that the mortar releases during cleaning, about 1/2 of it comes off the first time you clean (usually the part that you contact with the scraper) and then about another 1/4 with the next cleaning (for about 3/4 total loss) and after that, just a little at a time. I think I'm coming up on the 4th cleaning on mine and I'm going to take lots of pics and use that handy cheapo 'scope again and see exactly how much is left and in what density.
And for fun, a #4-40 threadcutting machine screw
And my fingerprint
Turbo, et. al.,
Could you please provide me with a link from ebay/amazon of a red, or red/blue LEDgrow light you recommend?
One that's powerful enough to grow well, large enough to cover the 13x11" sheets, and maybe be even slighltly water resistant?
Word on the street is that a submersible scrubber light will be available soon.
After some research, I went with the 30W LED's off ebay that others are having great reviews on. They should be here in 3 days.
I'm going to leave the one screen with my CFL/reflectors on, and
one screen with the new LED's-
Going to clean both at the same time ( I usually stagger the cleanings of each sheet),
and post the results up.
I wanted to post an update on the Mortar Screen process. After making quite a few of these, I think I've figured out the best way to make them, and reasons why other ways don't work quite so well. It's the little things that tend to make the difference.
First, I scuff up the screen using a wire brush drill bit attachment like this
I mark off the area that will be the "active" growth area, tape off the area that will go into the slot (+ a few extra rows), then clamp the screen down to a hard surface that I don't mind scratching up (like MDF). Then, at a relatively slow/medium speed, I run the brush over that area + some bleed around the edges in 4 directions, up/down, left/right, and both diagonals. Flip and repeat.
Second, I rough up the screen with a 12pt 10" saw blade, like this
But I don't spend as much time doing this as I used to - 1 to 1.5" overlapping circular motion going from one side to the other, repeat until all rough. Then I reverse the circular direction and make another pass top-bottom. Flip and repeat.
Third, I cut the screen down to it's intended final size, then add some blue painter's tape to the un-roughed area to protect it from the mortar coating.
Now, it's ready for the mortar.
Mix the mortar, glop it on to the screen, and massage it in so that the whole screen is coated with a thick layer, maybe 1/4" thick. Flip it over and add more mortar, massage it in well.
Then I hold the screen over a garbage can and tap it hard with my fingertips - this knocks the excess off rather well while leaving behind a nice coating, and with enough taps the excess basically beads up and rolls off the screen so you get all the members covered really well and none of the holes filled in with mortar.
For the curing process, you will want a semi-airtight container, like a Sterilite storage box or Rubbermaid tote. You don't want an air-tight seal. I tried ziplock bags and while it worked well, it wasn't "perfect" and I'm a bit of a perfectionist. There needs to be a bit of "breathing room", if even just the air in the container.
Lay a piece of wax paper down and place the screen on it. Don't remove the blue tape. Lay another piece of wax paper on top of that.
Next, you can either take a small wet cotton towel or a micro-fiber cloth, and lay that on top of the wax paper. The towel does not need to be sopping wet, but you want it to be mostly wet but not quite dripping. You don't even need a cotton towel, you can also use a few paper towels and get those wet and lay them down - works just as well.
Close up the container. Once a day, take the screen out and give each side a few spritzes with water and put it back in it's little wax paper and towel sandwich, and back in the tote it goes. Repeat this for 3 days.
On the end of the 3rd day in the container, take the screen out, remove the tape, and place the screen in a bucket of water. Change the water daily. After a week, you're good to go. To make it go faster, add some circulation (3 or 4 days, and you're good). I use a utility sink and a small pump I had laying around. As long as the screen isn't banging around, you're good (you don't want the mortar to get knocked off)
I had a video made up of this process, but I have to trash that due to it's lack of perfection. But I'll post one as soon as I shoot a new one.
Video of the Mortar Screen process
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