DIY Algae Reactor

As things go in this hobby, I find myself swinging from an algae free tank with no coral growth to an algae plagued tank with decent coral growth until the algae gets out of hand. Since the current thinking is that a nutrient free tank starves corals, there needs to be a way to balance coral needs with export rates. I’ve always been a fan of the idea of algae reactors, but never got around to putting one in my tank. The off-the-shelf options are expensive and/or big and I knew I could do better. This build has been happening over almost a year on and off, but I finally finished it and put it online a few weeks ago. Here are the details of my progress…

It all started with an awesome deal on this LifeGaurd Aquatics reactor from @Ento_Reefer:

I saw the potential in the reactor and it is the same size as my skimmer, so I figured I could swap out my skimmer for the reactor. The reactor has a built in pump and has nice baffles to keep the algae in. The first issue to tackle was to light the chamber. A lot of DIY builds use LED strings wrapped around the outside of an acrylic cylinder. That leads to cooling issues and microfractures in the acrylic, not to mention it doesn’t look great either. I decided to light this from the top with an LED grow light. It’s more polished, easier to control and won’t have heat issues.

First thing I had to do was replace the opaque top lid with clear acrylic… More on that in my next post.


Great idea, the suspense is killing me, I like what you did there…


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Just to be clear, so you are no longer using your skimmer, you will only be running the algae reactor.


That’s right @houndsbayman. Skimmer free!

I made one of these also…to deal with the heat micro cracks issue -I used rigid airline hose attached to the chamber all around to act as a “spacer” for the LED’s …I built it and have LED grow lights for it , but never used it -as my nitrates are zero with my plenum setup and phosphates are now maintained by a 12x12 polyfilter in my eheim…phospates are low now…
so if anyone wants a ready to use algae reactor , It’s for sale , I guess…can post pics if needed…

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Cutting the Acrylic Lid
Lucky for me, I have an office in an awesome makerspace NextFab. I have access to insane equipment as a result. For this part of the project, the laser cutter was my go to. I quickly modeled the lid and the internal filter so I could cut them from clear acrylic. Here’s a little look at how that process goes cutting the filter:

Step one was to replace the opaque lid (top white part) with a new lid with a clear center (the rest of the parts).

Just a picture of the acrylic welding process of joining the white acrylic with the clear acrylic

And the final product next to the original. This is before I added the filter part. Had to order some acrylic rod, so this is where I stopped.

Next step is to address the reactor chamber itself which is clear. That’s not gonna work! More in the next post.

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Wow Adam. Great job modding that filter. I cant wait to see the finished product.

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