Freshwater Algae Scrubber on 600L Oscar tank

[Murrayb]

Approximately 9 months ago I implemented a DIY algae scrubber in my 600L Oscar tank in a bid to reduce the necessity for water changes and decrease my nitrate levels. The tank had been established for over a year at this stage and I was having trouble keeping the nitrates under control. It was installed under the tank and the basic idea is that tank water is passed over an inclined slope above which are three 4.5W 2600K LED bulbs. The algae grows rapidly under these conditions(20hrs light a day) and is periodically scraped off, reducing the nitrates in the system. This short clip shows where the algae scrubber is located, https://gfycat.com/DeadlyDearestDavidstiger , and the growth after the initial few days. It took several weeks but the scrubber then began to produce algae at a steady rate, with this video:

showing it approx 4 days into the 8 week growing/cleaning cycle. The scrubber has been largely successful as it has reduced the need for water changes while using a small amount of electricity. Below are additional images of the tank setup which also includes DIY filter system, stand and tank canopy.

http://imgur.com/a/xa9Dh
https://youtu.be/FqEzQAIZoGw
Additional video of feeding and some of the recent convict fry. The total list of tank inhabitants is: 2 x Oscars, 7 x Silver Dollars, 2 x SAEs, 1 x Common Pleco, 1 x Red Tailed shark, 2 x Convicts and many convict fry.

 

[Fish Eat Fish]

Do you have any estimates on the effectiveness? As in ppm nitrate reduction? Or some other metric?

I've always wanted to try this as I previous dove into a mangrove refugium that wasn't very helpful. Algae seems a much better route!

 

[Murrayb]

It is difficult to say as my nitrate testing frequency is patchy at best but I can confidently say that my water change schedule has approximately halved(20% weekly to 20% every 2 weeks) with no long term increase in the nitrate levels. For me this was the key idea as I am not always present to do the water changes at the frequency that was required before the algae filter was introduced. If I wanted a significant reduction in the nitrates along with less water changes I suspect I would need to increase the surface area of the scrubber and therefore add more LED bulbs/higher wattage bulbs. This idea started off as a test and I initially thought that the 4.5W LED bulbs would not be sufficient for any growth but they seem to be doing the trick. If I knew initially that it would be effective I would have been more scientific and taken regular nitrate reading while maintaining the pre-existing water change levels. Sorry I cant give more scientific values. As for the algae filter vs mangrove refugium, I suspect that they will both work well but with the mangroves you will need a larger space to grow them and it may take more maintenance as you will need to trim them to maintain a optimum distance/converage from the bulbs.

 

[Fish Eat Fish]

The problem with the mangrove is that as you said you need a lot of space and they just require more factors to be correct than algae. Algae seems just simply need moisture and light with lots of wiggle room on how much moisture and light you provide! I also suspect that algae grows more (take more nitrate out) than even a mangrove refugium 10 times footprint of your algae tray. One day I may give this a try as well! Great job with yours