I visited my friend Will to see how his tanks are doing. Will has two aquariums, a 75-gallon mixed reef and a 275-gallon SPS dominated tank both running some variation of Aquaforest.

Every now and again I like to take a field trip to other people’s aquariums, especially some of the local hobbyists that purchased corals from us. Seeing the same corals day after day normalizes expectations of that coral. It is really easy to settle into the appearance of corals here and think that is as good as a particular coral will look. It is revealing to see how a coral is doing in another person’s tank because sometimes they will have incredible success with a coral and we can learn a lot from the visit.

Before we jump too far into that, let’s do a quick overview of the two tanks. The first tank is this SPS dominated 275-gallon reef savvy tank. It is an absolute hulk of a tank featuring 3/4” thick glass and an oversized external overflow on the side. Seeing this tank in person was one of the factors that got me considering a reef savvy tank for myself.

This tank is illuminated by a combination of T5 and LED, but the majority of the light is coming from two 36” ATI T5 fixtures. The bulbs are all blue plus with a single actinic giving the whole tank a deep blue look but without the heavy black light actinic look that all blue LEDs would give.

The flow in the tank is provided by a return pump as well as a couple gyre power head pumps. Will was not happy with the way the sand blows around the tank and a few days after I shot this footage, he removed all of the substrate in favor of a bare bottom tank.

The circulation to and from the sump is pretty straight forward. The water cascades down to the sump from this external overflow box that has three drain lines in a Bean Animal configuration. This type of overflow is popular with hobbyists looking to make as quite an overflow as possible. The first drain is stopped back with a valve so that the water level in the overflow box is above it. This creates a bubble-free siphon that handles the majority of the water. Most of the noise an overflow makes is the bubbles going through the pipe, so having a bubble-free siphon all but eliminates this source of noise.

The secondary drain establishes the desired max water level in the overflow box. Ideally the first drain would be set so that only a small trickle goes into this pipe so it makes as little noise as possible.

In theory, the first drain could maintain a stable water level on its own, but in practice it’s not reliable. If you have an overflow box with a single drain, stopping it back without a secondary or tertiary backup drain is unwise. Over time, organisms will grow in the pipe or a snail might make its way into the box and block the drain… any number of things could happen to throw off the delicate balance of that primary drain.

This secondary drain acts as an insurance policy. Some hobbyists implement this secondary drain as a Durso style standpipe, but Will here decided to leave it just open. The main benefit of this secondary standpipe is that it sets the level of the water in the overflow box to minimize the noise created by the water flowing into the box. Too much of a drop from the teeth of the overflow box and it will sound like a waterfall.

The last drain is the emergency drain. This theoretically should never come into play but in the event that both the primary and secondary drains fail for some reason, this final drain is sized to handle the full flow of the overflow to prevent a spill.

The sump is a vertex brand sump and it is like a tailored suit to both fit into this space and to house all the equipment and probes. For hobbyists with limited space either in a back room like this or under an aquarium stand can appreciate a product like this that is neatly organized.

I have a soft spot in my heart for vertex products because I am a freak when it comes to quiet equipment and always found their line of skimmers to be very quiet. They just don’t make ones big enough to handle giant aquaculture systems, but I’m sure anything is possible custom.

In addition to the protein skimmer, this sump also has some media reactors for carbon and GFO and replenishes major and minor elements by way of the Neptune DOS pumps.

As I mentioned before, Will likes the Aquaforest line of products, so he’s using their salt and all the various additives on a dosing schedule. Speaking of salt, one change he made to this system from the last time I saw it was the addition of another Neptune DOS pump to do automatic water changes.

Aquaforest is associated with ultra low nutrient methodology. The way that I understand it is for the hobbyist to provide a carbon source to promote the proliferation of bacteria to directly consume phosphate and nitrate from the water. This bacteria would then get removed by the protein skimmer thus cleansing the water. Encouraging bacterial growth like this and then removing them from the system drastically drops the nutrient levels in the tank. Starting from that low nutrient baseline the hobbyist adds back food and supplements designed to promote colors and growth in corals.

The result in an SPS dominated tank when things go right are these pastel-like colors with great polyp extension. Critics of this method point out that these corals are basically starved down to express this coloration and are one stress event away from a crash.

In a time where people are looking for lower maintenance methods, this is the opposite end of the spectrum where the hobbyist needs to be on top of everything to not only achieve the desired aesthetic results but to avoid an all out crash. Personally I have not had a good experience with ANY ultra low nutrient carbon dosing methodology, but this is something that Will has been doing for a long time. Prior to running Aquaforest, he used the zeovit and the Red Sea carbon products.

Let’s move on to the other tank. This mixed reef is set up in a 75 gallon rimless Elos tank. This tank is the thing that really got me thinking about my own system and coral biology in general. It runs similar lighting and filtration as the larger SPS reef in the other room but is slightly higher in nitrates which is working really nicely for corals that are known for liking higher nutrient levels. The nitrate levels are still low sitting at .5ppm in the sps reef and 2 ppm in this mixed reef.

Take for example these neon green Nephthea. They are not a difficult coral by any stretch, but they are a coral that loves high nutrient and doing great in this tank. The LPS are even doing well. Often times when you pair an ultra low nutrient method with these corals they take on a bleached look. It’s not even so much a nice pastel appearance that the SPS take, they just look like they are about to die. Here though, they are retaining their healthy coloration and in the case of the hammer and goniopora in the back are growing nicely.

The goniopora is especially interesting to me because this is a coral that I CAN keep in my system, but it never flourishes. In fact, this is a piece that Will purchased from Tidal Gardens years ago, but it is so much happier in Will’s tank than it is in mine. This coral has been fragged a number of times and those cuttings have been repurchased by yours truly but I haven’t yet been able to culture these long term at the greenhouse.

Wills systems obviously are very different from mine but if I had to guess one major difference that might be the key in his success is with these corals in particular is bacterial feeding.

The role of Bacterial feeding in coral biology is one of those topics that has been well documented in scientific literature for decades but is not something that hobbyists tend to pay a lot of attention to. The last time I did serial dilutions to test for bacterial levels was way back in college for microbiology lab. I’ve never done it since, but it is something that I am becoming more and more interested in.

There are several publications on the topic, but one in particular that I found interesting was from Coral Reef in 1989 by Schiller and Herndl. Basically it took a look at the interstitial space around certain stony corals. They looked at a few different parameters such as ammonia, nitrite, nitrate, phosphorous, and bacteria levels in the interstitial spaces compared to the ambient water column. What they found was that there were lower concentrations of dissolved organics in the interstitial space with an associated uptick in the concentration of bacteria.

Corals may be feeding on bacteria directly or indirectly attracting microbe-feeding zooplankton that they then trap and consume, but it is interesting that the corals studied grow in a fashion that not only optimizes access to light and flow but also to maximize bacteria farming opportunities in the interstitial spaces between branches.

I’m now interested in finding ways to promote bacterial growth in my own systems as a food source for corals without the drama of a full-blown ultra low nutrient system because as I have mentioned, every past effort to go down a carbon dosing path has not worked out for me. What do you guys think?

Anyway, I hope you enjoyed this field trip to Will’s tank. Until next time, happy reefing.

Than Thein

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