Tips for Starting a 5-Gallon AIO Reef?

[DaTinyReefer]

Hey everyone,

I’m just getting into the saltwater hobby and starting small with a 5-gallon all-in-one tank (AIO). My goal is to keep things simple, learn as I go, and eventually work my way up to a bigger system in the future.

Right now, I’m in the planning phase and would love your input on:

• Stocking ideas: Looking for suggestions for hardy beginner corals and maybe one or two cool inverts — not sure if a single fish would be too much bioload.
• Maintenance: How often do you guys recommend water changes on such a small tank?

I know small tanks can be challenging, but I’m excited to take it slow and do it right. Would appreciate any gear recommendations, tips, or beginner-friendly resources you wish you had when you started.


Thanks in advance! Looking forward to learning from you all and sharing progress pics as things get going.

 

[tbrown]

I kept a single clownfish, some peppermint shrimp, and some snails and hermits in my old 5 gallon. The clown was likely too big long term.

There are some nano gobies that would work in a 5 gallon.

I like Hector's or Rainford Gobies for smaller tanks for some added color and algae control assistance.

Clown Gobies can be a cool nano fish as well.

Soft corals and easier SPS like Montipora are decent for color.

Water change frequency would be determined by your needs. If you dose and have a decent nutrient export, water changes are less necessary so frequency can be spread out. Without dosing, a 1-2 gallon water change weekly helps a lot. Less frequent changes can make more instability in the tank.

 

[toothybugs]

Small? Start with a 20 and put a couple baffles in a 10 to make a little sump. Most of the smallest pumps available will fit a20 well but be way too much for a 5.

Your equipment costs will be very similar, you're gaining quadruple the water volume so chemistry is easier, and your livestock options are a LOT better.

 

[GHOSTLY]

Hey everyone,

I’m just getting into the saltwater hobby and starting small with a 5-gallon all-in-one tank (AIO). My goal is to keep things simple, learn as I go, and eventually work my way up to a bigger system in the future.

Right now, I’m in the planning phase and would love your input on:

• Stocking ideas: Looking for suggestions for hardy beginner corals and maybe one or two cool inverts — not sure if a single fish would be too much bioload.
• Maintenance: How often do you guys recommend water changes on such a small tank?

I know small tanks can be challenging, but I’m excited to take it slow and do it right. Would appreciate any gear recommendations, tips, or beginner-friendly resources you wish you had when you started.


Thanks in advance! Looking forward to learning from you all and sharing progress pics as things get going.

Hey im actually running a 6g fluval betta tank atm with sps and mixed

Im more coral oriented so I actively chose to avoid fish in a tank this size just because I felt the nitrate would fluctuate too much. Currently in a 6g ive got 1 cleaner shrimp, 3 ceriths, 2 blue legs and I feed 2 marine pellets a day to maintain a nitrate level of 3

I do a water change every 3 weeks up to 25% to replenish the calcium uptake of my acros. I
use red sea blue bucket and maintain a calcium level of 430 and alk of around 8. Keeping pH stable by running my refugjum 4h at night

As for some tips for a small tanks like us is to invest in an ATO. In a big tank water evaporation has less of an effect as there's more water volume. In a small tank water evaporation can cause big changes which can stress coral. I found not to worry about small things anymore. There's not a need to fiddle around with what works. I've found my water changes replenish and my biweekly dosing of aminos have given me success

If you do want a small tank this is really good advice but there are also lots of prebuilt options. Evo 13.5, waterboxes, and lots of fluvals are easy to change to your needs

Small? Start with a 20 and put a couple baffles in a 10 to make a little sump. Most of the smallest pumps available will fit a20 well but be way too much for a 5.

Your equipment costs will be very similar, you're gaining quadruple the water volume so chemistry is easier, and your livestock options are a LOT better.

 

[Calmwaters]

I had upside down gobies, sexy shrimp and a Porcelain Crab in my 5 gallon until I made a mistake that caused me to lose them recently. I have since replaced the 5 sexy shrimp and the Porcelain crab and added a pompom crab. Today I'm picking up a clown goby from my local fish store for it. I love sitting and watching the tank as I have my morning coffee before with each day.

 

[Hunna’s Stunnas]

5g is perfect for a sexy shrimp and/or pompom crab tank. For a fish, you could do like a little citron/clown goby.

For recommendations, an ATO is a must for smaller tanks. Evaporation will cause much larger swings than it would in larger systems. They sell ~$8 plastic ones that use everyday plastic water bottles to store the RODI water. Super basic but works great, it’s what I use for my Deskmate.