6.8 Gallon Reef - MY FIRST SALTWATER TANK - (Imagitarium Frameless Freshwater Aquarium Kit, 6.8 GAL)

[dooren]

Introduction​

Hello! As the title suggests, this is my first reef tank. I'll use this post primarily to document the aquarium's progress over time. I'll share what I'm doing and learning, hoping it might help someone along the way.

I studied aquaculture, and I already have a densely planted freshwater tank and a blackwater tank for some exotic bettas. This is my first attempt at a saltwater tank and working with corals, so expect a few mistakes here and there. I’ll also share my experiences to get feedback from more experienced reefers like you.

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Why Such a Small Tank for My First Saltwater Setup?​

I wanted to start small for several reasons:

1. Budget: I aimed for something affordable but visually appealing.
2. Space: My available space was limited, and I decided to repurpose the space used by a 10-gallon freshwater tank I dismantled.
3. Focus: I’m not interested in keeping fish at the moment, so a smaller volume seemed more manageable.
4. Aesthetics: I wanted a compact, aesthetically pleasing setup starting from the tank itself.

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What Are My Expectations for This Tank?​

My goal is to create a healthy tank full of soft and beginner-friendly LPS corals. I envision a vibrant, dynamic, and visually engaging aquarium.

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Tank and Equipment​

Tank:​

• Imagitarium Frameless Freshwater Aquarium Kit, 6.8 GAL

Equipment:​

• Aquaneat 265 GPH Submersible Water Pump
• Hygger Smart Mini 50W Heater
• Useek AT-200 ATO
• Hygger HG088 30W Light
• Fluval 0.3 G Breeding Box (Refugium)
• Light included with the tank kit (for refugium)

Salt:​

• Reef Salt Plus

Substrate and Aquascape:​

• CaribSea Arag-Alive Fiji Aquarium Sand, 10 lbs (Pink)
• Moani Dry Rock, 5 lbs

I bought a single 5-pound rock, broke it into smaller pieces, and glued them together using cyanoacrylate and crushed rock dust to achieve the desired shape.

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Backsump Setup​

The tank includes a spacious backsump with mirrored chambers for the two water inlets, both connecting to a central return chamber.

1. Filter Media:
   • Stock sponges included with the kit.
   • Added filter floss and ceramic rings in one chamber.
2. Pump Upgrade:
   The included pump (160 lph or 42.2 gph) seemed underpowered for the tank’s 6-gallon volume. I upgraded to an Aquaneat 265 GPH pump, but it was so strong that it disturbed the sand bed. I reduced the flow to its minimum and pointed the outlet upward, though this occasionally caused minor splashes.
3. Heating and ATO:
   The return chamber houses both the heater and ATO sensor comfortably.

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Refugium​

I added a Fluval 0.3 G Breeding Box as a refugium to increase water volume and help manage nutrients. It fits well in the backsump with minor cable adjustments. I used the included tank light for the refugium and covered it with black cardboard to block excess light. Chaeto algae was added a few days later.

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Timeline​

Day 1 (12/21/24):​

• Set up the tank and prepared the water.
• Adjusted salinity to 33-34 ppt using a budget refractometer.
• Added Biodigest-Prodibio to seed beneficial bacteria (opinions on its effectiveness vary, but it seemed to work for me).
• Set the heater to 78°F and added an additional thermometer for accuracy.
• Ran the lights on a 6-hour cycle at low intensity (white and blue combined).
• Initially used a Hygger Mini Wave Maker (1600 GPH) but later removed it (details below).

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Days 2–14:​

• Installed the refugium, ATO, and other equipment as they arrived.
• Reduced pump flow and added sponge to lid edges to dampen noise.
• Fed a pinch of fish flakes every 2-3 days and monitored nitrogen compounds (ammonia, nitrite, nitrate) using an API test kit.
• By Day 10, nitrogen levels stabilized near zero, and I increased feeding frequency.
• Observed uneven sand distribution due to flow; removed the wave maker and rearranged the sand.

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Day 15:​

I visited a nearby city with marine aquarium stores to buy supplies (coral dip, glue, test kits) and couldn’t resist picking up:

• Corals: Duncan, Acan, Zoas, Organ Pipe Coral, and a live rock with Mushroom Corals.
• Clean-Up Crew: 3 Astrea Snails and 2 Nerite Snails.
• Chaeto algae for the refugium.

After acclimating, I dipped the corals in Seachem Reef Dip, rinsed them, and placed them on frag racks. All corals opened within an hour, and I discovered an unexpected hitchhiker—a Emerald Crab—on the live rock. Research suggests they’re reef-safe, so I added it but monitor it closely.

Increased light intensity and photoperiod to 9 hours/day and run the refugium light 24/7.

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Day 16:​

Corals showed healthy growth, with some extending further. Water parameters were stable:

• Salinity: 34 ppt
• API Tests:
  • pH: 8.2
  • Ammonia: 0 ppm
  • Nitrite: 0 ppm
  • Nitrate: 0 ppm
  • GH: 125.3 ppm (7)
  • Calcium: 420 ppm
• Salifert Tests:
  • Magnesium: 1305 ppm
  • Phosphate: 0 ppm

Everything seems to be in place except for the phosphate levels. I'm not sure if the algae have already consumed it entirely, but I hope that by feeding the corals, I can maintain it at a concentration of 0.03 ppm.

Snails appear fine; Nerites hide in the rocks during the day and emerge at night, while Astreas stick to the glass near the top.

For now, I’ll keep observing how the corals and other inhabitants are doing. In a few days, I’ll try feeding the corals. I’m also planning to wait until the additional corals arrive and then attach the ones that are already settled to the main rock.

I’ve been considering adding three Sexy Shrimp, but I’m still debating it.

 

[dooren]

For anyone wondering, this is how the back of the tank looks like, the refugium fits perfectly.

I also forgot to mention that one of my goals for the tank is to minimize or ideally avoid nutrient dosing. I hope to replenish what’s needed solely through water changes, but time will tell.

 

[dooren]

Update: I temporarily moved the emerald crab from the main display to the refugium. It was picking at the Acan coral, so I’ll keep it there until I find someone to rehome it.

I imagine the tank doesn’t have enough food for the crab yet, which is likely why it went for the coral.

 

[dooren]

Day 19:

Small patches of brown algae have started to appear on the refugium, ceramic rings, and the scape. The refugium seems to be functioning well; the algae is covered in bubbles, which I understand indicates active photosynthesis. All the corals appear healthy, and I spot-fed them with 1 ml of diluted Red Sea AB Plus.

Additionally, some new corals arrived today: another Duncan, a pair of Acans, and four different Zoanthid varieties. They seem to be acclimating well so far, but I'll monitor them closely in the coming days.

For now, I’m still avoiding gluing anything onto the rocks. I plan to wait about a week before making any permanent placements.

 

[dooren]

DAY 21:

• Salinity: 34 ppt
• API Tests:
  • pH: 8.2
  • Ammonia: 0 ppm
  • Nitrite: 0 ppm
  • Nitrate: 0 ppm
  • GH: 107.4 ppm (6)
  • Calcium: -
• Salifert Tests:
  • Magnesium: 1275 ppm
  • Phosphate: 0 ppm

 

[dooren]

DAY 26:
I’ve been working on setting up a feeding schedule. So far, I’ve been occasionally feeding Red Sea AB, and yesterday I spot-fed mysis shrimp to the acans, duncans, mushrooms, and some lucky zoas. Later this week, I plan to add Reef Roids to the mix.

A couple of days ago, I did a one-gallon water change, but I’ve also been doing smaller water changes recently to acclimate corals, dip them, and make other adjustments.

Some new zoas and acans are now in the tank, and I finally glued everything into place.

I’m starting to enter the “ugly phase.” Some brown algae has appeared on the glass and rocks, but I think the refugium is doing its job since it’s still pearling, and there hasn’t been an algae outbreak yet. Some bubble algae hitched a ride on my organ pipe coral and has been growing a bit. It’s still confined to the frag for now, so it doesn’t bother me much—but we’ll see how it goes.

My pH and gH have risen slightly, which I assume is due to the water changes. But everything seems happy.

• Salinity: 34 ppt
• API Tests:
  • pH: 8.4
  • Ammonia: 0 ppm
  • Nitrite: 0 ppm
  • Nitrate: 0 ppm
  • GH: 143.8 ppm (8)
  • Calcium: 440 mg/L
• Salifert Tests:
  • Magnesium: 1410 ppm
  • Phosphate: 0 ppm
    
    

 

[dooren]

*Ive been testing kH not GH, I'll correct it from now on

 

[dooren]

• Salinity: 34 ppt
• API Tests:
  • pH: 8.2
  • Nitrate: 0 ppm
  • GH: 89.5 ppm (5)
  • Calcium: 440 mg/L

GH seems low, did a 1.5 gallon water change

 

[dooren]

Salinity: 34 ppt
API Tests:

• pH: 8.2
• GH: 8
• Calcium: 440 mg/L

My coral feeding routine consists of Reef Roids, mysis shrimp, and Red Sea AB Plus, alternating every other day—one day I feed, the next day I don’t. Recently, I tried feeding New Life Spectrum tropical fish pellets since their ingredients are the same as their SPS coral food, just in pellet form instead of powder. Surprisingly, my Duncans, Acans, and some Zoanthids seem to eat them really well. Overall, all my corals are showing signs of growth, either by increasing polyp size or sprouting new heads, with the most noticeable growth in my Duncans and Acans.

Another big update is that I was gifted a pair of stubby clownfish. I wasn’t planning on adding fish yet, but since they came from a defective batch, it was either adopting them or having them culled. They’re still small and adjusting to the tank, so they’re a bit skittish, but they did manage to eat some crushed pellets.

With the rapid coral growth and the addition of the clownfish, I’ll likely be upgrading to a 10–15 gallon tank sooner rather than later.