My DIY, PVC ATS w/ LED's

We sure love acronyms in our hobby don't we .

I build a do-it-yourself (DIY) polyvinyl chloride (PVC) algal turf scrubber (ATS) with light emitting diodes (LED) that I bought from Amazon. I'll try and describe it for you here with lots of pics to follow. I'm really thankful for all the people on this site, so this is my way of trying to contribute to the community.

DIY: First and foremost, if I could afford it, I WOULD BUY one of Turbo's new units. There is

nothing better than a turnkey system that is tried and true. But there were >100 people ahead of me on the waiting list, and I have a wee algae problem in my tank that I'd like to conquer. Plus I really enjoy building things, so I opted for a DIY for my first ATS. For the record, I mean if I could afford to wait - I would've shelled out the $$ to buy Turbo's Rev 4. ​

PVC: Huh? This is strange... As I was wandering around Home Depot looking for sheets of

acrylic to build the ATS, I found something called PVC Trimboard and I got an idea. I bet I could build this thing from PVC 'lumber'! I have a bit of experience with woodworking and figured it would be worth a shot. (Here's a link to the product)

The product is designed for use as window trim or house siding, and because it is 100% PVC it won't rot. It is not very dense and it is easy to work/cut. Apparently, there is another (similar but more dense) product that is designed for building patios/decks or for structural outdoor furniture.

But PVC lumber in the aquarium? Hmmmm.... I haven't seen any other DIY equipment made from this product so I was a little nervous at first. But it is 100% PVC, so really, it ought to be just fine. If my tank crashes I'll definitely turn this into a 'For the love of God, don't use PVC lumber for anything ever in your reef tank' thread!
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LED: I am not electrically-inclined and I wanted to buy a LED light that would suit my

needs. So after reading another post in this forum I decided to purchase these lights from Amazon and try 'em out. So far I'm happy I spent the money on 2 of these 20W lights. They appear to fit the current recommendations in terms of wattage and spectrum 16 reds (660 nm) & 4 blues (445-450 nm). I am running them on a timer from 6pm to 10 am (16 hours total), but this may change depending on future growth/needs.
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TANK: I have a 90 Gallon mixed reef tank that has been running for >1 year (cycled &

inhabited with livestock for 12 months). I used dry Pukani rock and attempted to bleach out ('cook') as much dead organic matter as possible before I set the tank up. But I think it is still slowly leaching phosphorus. I have had the typical new tank blooms of diatoms, hair algae, etc... All in all, things have gone pretty well for me so far. I have been running GFO for a few months now, but the hair algae is still a nuisance. I have a low bio-load and do not overfeed. Along with my coral, I have 2 clowns, a coral beauty, a mandarin dragonet and inverts.
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DESIGN: Well, like any good DIY'er, I did my research and tried my best to learn from

everyone else's experience. There is an awesome wealth of info in this site, and I made good use of the threads in the 'Resources' section. Some of them I read and re-read a few times .

I have a Herbie Drain set-up and a sump in my basement with all the ugly/noisy equipment. I measured the flow coming through my main drain (equipped with a true gate valve to tune the siphon) and I got about 245 gph of flow. My return pump has a decent amount of head pressure to overcome (~8 feet?) so that is the flow I'm left with. I plan to increase my fish load over time. Maybe I'll get to a 2 cubes/day feeding load? Admittedly, I still find this metric hard to decipher but we need some way of quantifying the nutrient load... So I determined that I wanted a 6" by 6" screen, lit on both sides. I figured the 2 x 20W LED's would do the trick. If they are too powerful then I hope to compensate by reducing the photoperiod.

I had to design an ATS box that could hold water. After putting together a design on paper, I set out with my 70's-era table saw had a lot of fun shredding plastic wood. I cut dado joints to join the bottom and sides. I made sure the cuts were relatively smooth, and if needed used a file and/or sand paper to quickly smooth out the cuts. I used PVC primer and cement on all the joints.

Because I bought 1" by 10" by 8' boards, the 'lumber' was actually 3/4" thick by 9 1/4" wide. This was wide enough to make the bottom, top, and the two narrow sides. But the wider sides that housed the window for the lights needed to be bigger. So I joined two pieces together using a double rabbit joint (lap joint).

Does it hold water? Yes! Any leaks? No! Alright!

I cut a rectangular hole slightly bigger than the size of my lights (lights are 180 mm x 140 mm). I bought a thin sheet of Lexan (polycarbonate) and cut out two windows on the table saw. They overlap the cutout by ~1" so there is plenty of surface area to seal the window to the sides. I used GE Silicon I for this and it has held up very well so far. I let the silicone cure for 48 hours. Note: in normal usage this seal will never be submerged.

I used 3/4" PVC for all my piping. I cut the slot using my table saw. I set the pipe in position with my fence and slowly raised the blade up into the pipe, then moved the pipe along the fence into the blade. I cleaned up the cut and slightly widened it using my Dremel tool. The final slot length is a fraction over 6" and a hair over 1/8th of an inch wide. I found a great PVC union at Lowes that I really like. It is about 5" long and I find it easy to open/close. Easier than the other ones. Plus it has a gasket that fits over the pipe (see pictures), which provides a solid seal better than an o-ring that can wear out over time or get crushed by improper connection.

I attached the screen using zip ties (loose not really tight). I bought plastic grommets that snap in place at my local hardware store. I also made a simple 'drip stop' using leftover tubing from my skimmer and zip ties. Not my idea - something I read on a forum somewhere. Easy and effective.

I used a 1 1/4" keyhole saw bit to drill out a hole for the drain pipe connections. I had to slightly widen this using a sanding tool on my Dremel to make a really snug fit for the 3/4" PVC pipe. I made two hole, one for a main drain (equipped with a cheap ball valve) and one for an emergency drain that comes out the side ~2" from the bottom. Doing this allows for an imperfect Herbie Drain setup on the cheap. I didn't want to spend the $ on an expensive gate valve. I was able to tune the siphon with the ball valve.

One trick: I used a bunch of the 'saw dust' plastic shavings to plug up gaps that I felt were a little too large for me. When I was gluing up joints (the drain pipes specifically) I mixed some shavings with the PVC cement and packed it into the joints to build up the connection a bit. I just used my fingers. It seems to have worked well.

Another line of defense: I sealed all seams on the outside of the ATS with silicone. Just to be safe. If any of the PVC joints didn't take 100% (which didn't happen), then maybe the silicone would help me out... Plus I sized the ATS to sit inside of my sump in case of a catastrophic leak.

I made a false bottomed floor (yes I borrowed the idea from Turbo). After some searching I read the purpose of this is to reduce the likelihood that algae clogs up the drain pipe. I made wee little legs for the false bottom with 1/2" PVC pipe and drilled holes so I could stick them in place. Once I got the ATS running I found it was pretty loud. So I cut up a small piece of blue foam and placed it in there to help soften the splash of water (not sure it helps much). Either way, it isn't so load that I hear it when I leave the area of the sump.

I used the normal canvas screen that is recommended. I left a smooth strip (1 1/2" wide) near the slot to discourage algae growth. I roughed it up with a hole saw, then mixed up some concrete I had laying around. I picked out the large stones, then smeared it all over the screen and left it covered in wax paper for about 2 days. I took it out and washed it off and a light coating of calcareous mortar did remain. This may help get the hair algae established. See initial growth in pics below. I haven't incorporated a light blocker yet. I may need to in the future - time will tell.

Finally, I made a stand for the ATS out of scrap pieces. It allows the ATS to sit on top of the stand, centered inside my sump in the middle compartment.​

Well I have had it online now for 9 days. The first day I was worried because the flow seem to be preferentially directed towards the one side of the screen. This seems to have corrected itself now and flow is pretty even across the width of the screen. There is a good 'sheet' of water flowing down the screen. Growth of green algae is starting I'll keep updating this thread every now and then to report success/failures. I think people may be interested in how well these lights perform...

 

A couple more pics.

 

And a few pics of my young tank (showing off some of my soon-to-die algae)

 

Forgot to mention that I'm open to all suggestions for improvement/questions. For starters, I wonder if I should reduce the photoperiod? I notice a little less growth in the center of the screen where the light is most direct. Perhaps photosaturation? Right now lights are on for 16 hours.

 

Thanks for the suggestion. Think plastic food film/wrap, folded up into a square, would work as a decent light diffuser? I'm giving it a shot now. The lights don't get hot (hardly warm even). Nowhere near as hot as a microwave. I'll take it off if/when I get better growth in the middle.

 

Thank you both for your input! This fixture doesn't really get very hot. After several hours on time, I am able to place my entire palm directly on the glass in front of the LED chip and leave it there. However, the acrylic diffuser would likely work better so I'll try and pick up a tile of it this weekend.

 

I picked up a diffuser panel last weekend and cut it to shape. After reading a little more carefully I see you suggested to make a smaller diffuser than I've made (mine covers the entire light). So maybe I'll trim it down.

I did reduce the photoperiod to 12 hours (from 16). I'll leave it another week to see if the growth fills in, but maybe I should reduce the lighting time a little more.

These pictures show growth after 3.5 weeks of the ATS going on-line. Would this be considered a 'good start'? Open to suggestions.

 

The product I used is made by the same manufacturer. How did you determine that it is treated with a fire retardant? I would bet it is listed as mold and mildew free not because it is treated with a fungicide, but because it is made of pvc (not wood, which is susceptible to rot). This is plastic - pvc is a kind of plastic that can take various forms. We use it in flexible tubing with barbed fittings (vinyl tubing), or semi-rigid piping (spa tubing), or rigid pipe (sch 40 or 80 pvc). I would do as I did and phone the manufacturer to ask questions.

My ATS has been running for 4 weeks now and I have not lost any fish or seen any noticeable harm to coral or invertebrates. Actually my coral are looking better and better. Good colour and growing strong. I understand your hesitation - I was hesitant at first. But so far so good.

 

Thanks for the suggestion. I've seen that cool idea on other posts. I may need to do that down the road, but for now the screen is loosely set into the slot and I can easily rotate the screen out of the way to clean the slot. And because the union connection is so easy to remove I can take it apart from there each time to clean the screen. I have a ball valve upstream to completely shut off the flow. Because I have a Herbie Drain setup on my tank all the flow goes down my emergency drain (temporarily) when I shut off the flow to clean the screen.

I haven't yet cleaned it because I'm letting it get established. Looking at post #12 above, do you think growth is coming along ok? Or is it slow to establish? Wondering if I should do anything different or leave it be?

 

Okay - thanks! I'll stop worrying and let nature take it's course! Here's a pic from today. I'll stop posting in this thread now and create a new one under the new sub-forum that was just made to assess the effectiveness of after-market lights.