2.5 gallon Pico tank build

[mpw213]

Hi Everyone!
I’m a bit late to start a build thread because the tank has been going for about 9 months, but I figure better late then never!

This is a 2.5 gallon mixed reef tank and my first serious reef tank (had a very basic tank 20 years ago). It’s been a blast and I went from thinking it would be a fun side project until I buy a house and get a big tank, but I’m fully obsessed with pico tanks now .

I’ll keep posting updates to the thread and happy to answer any questions.

Build:
Tank: PNW 2.5 gallon lagoon AIO
Light: AI Prime 16 HD
Flow: smallest power head I could find on Amazon
ATO
5 versa pumps for auto water changes and dosing
Live rock 5 lbs
Sand: Carib live sand

Fish:
Clown goby
White cap goby
Dracula goby

CUC:
2 blue leg hermit
1 astrea snail
2 bumblebee snail
1 porcelain crab
1 sexy shrimp
1 stomatella snail (hitchhiker)

Coral:
(Mushroom)
Green discoma (3)
Sunkist bounce mushroom
Jawbreaker mushroom
Orange Yuma
Doughboy mushroom

(Zoas)
Bam-bans
Scrambled eggs
Antimatter
Incinerators
Sunny D
Stratospheres
Halle Berrys
Psychosis
Blue hornet
Jurassic park

(SPS)
Pavona
Birds nest
Montipora

(LPS)
Banana grail? Torch
Duncan
Gold hammer
Holy grail micromussa
Blue raven blastomussa
Acans
Candy cane
Mummy eye chalice
Flaming Bugatti chalice

(Misc)
Atomic broccoli macro
Papaya clove polyps
GSP

Initial setup (6/2025)




First corals (7/2025)


Some more corals and clown goby (8/2025)




Got carried away at a frag show (9/2025)





Lost the torch and added a macro (11/2025)


Added my dream torch (banana) 1/2026) and got an actual camera filter




Where I’m at now (2/2026)

 

[Tahoe61]

It's fantastic!
What are you dosing?
How much water gets changed out at a time?

 

[mpw213]

It's fantastic!
What are you dosing?
How much water gets changed out at a time?

Thank you! I dose alkalinity (Red Sea foundation), magnesium, nitrate, and all for reef daily (and test daily). It’s definitely the worst part about keeping a small tank I think. I do water changes every day to every other day to keep phosphates below 0.1, usually about 500 mL. That part is super easy using versas. Soon I plan to put everything on a schedule and hopefully test less frequently

 

[Tahoe61]

I dose nitrate as well and AFR.

What are you keeping your alk value at?

 

[mpw213]

I dose nitrate as well and AFR.

What are you keeping your alk value at?

I’ve been using the pure bicarb and AFR together because with only AFR my calcium will keep rising with the dose I need to keep KH stable. I try to keep it in the 8’s generally.

 

[mpw213]

View attachment 20260209_192120_1E0A8FFB-359A-4355-9BCC-4BD02A8FAD4D.mov

Hard to see but finally got a video of the white cap goby



And the Dracula goby is coming out nonstop after 3 days

 

[Gumbies R Us]

Following along!

 

[mpw213]

View attachment 20260214_141032_1A7B9B70-B784-42EE-B47C-C04C08E3600C.mov
Dracula goby barely hides now



Corals looking pretty happy, esp the torch, after a deep cleaning of the glass and back compartment yesterday

 

[mpw213]

Finally have all of the versas calibrated and setup. 2 for water changes, and 4 for dosing (all for reef, nitrate, alkalinity, and mg). Modified the lid to have 4 holes for the dosing lines to run through right on top of the power head.

 

[mpw213]

Tank is a bit cluttered from the rack after going to LEAR frag fest but got some new zoas and a super small Aussie gold torch that is grown from a colony that spawned in captivity. Planning to move the zoas after I get a single frag holder for the torch.

 

[newreefer 363]

What heater do you use

 

[mpw213]

What heater do you use

Sorry just saw this. I use an aquatop Pisces and a small tetra one for a betta tank. Both automatically go to 78F but I had them on an inkbird controller

 

[mpw213]

View attachment 20260402_191018_615A7C2F-CFC8-47A4-A693-78DE1E88B331.mov
Updated pics and finally got a video of my white cap goby (after he jumped last night and luckily I got him back in fast enough)

 

[fishy_fishy_fish]

Hi, just wanted to say that your tank has been a major inspiration for me with my first dip into saltwater!

I'm just curious, but have you had any problems with chemical warfare impacting your sps corals? And have the SPS corals been doing fine without random flow?

I have a 3 gallon at 4.5 months right now with softies and LPS but I'm looking into adding some Montipora and birdsnest. Can't find a wave maker small enough so was going to try a nano pump like you, and then was planning on large weekly water changes + smaller ones throughout the week to replenish minerals and take care of softie toxins, wondering in your experience how that would go? I am going with much lower tech, only a canister filter, heater, and light at the moment (but adding a nano pump).

Thanks for this thread, like I said it's been a great reference point for me!

 

[mpw213]

Hey! Thanks for the kind words. I don’t know of any chemical warfare but I do definitely have some coral deaths that could be from that (even today I had to cut some dying heads off my candy cane). I’ve had mixed experiences with SPS. My monti and birdsnest basically bleached out for the first 6 months and only now are starting to look nice and grow. And now I actually have an acro that’s growing which I didn’t expect.

And I actually do have a small power head in the back! It’s the smallest one I could find and happens to be a cheap Chinese one off Amazon

 

[mpw213]

Hi, just wanted to say that your tank has been a major inspiration for me with my first dip into saltwater!

I'm just curious, but have you had any problems with chemical warfare impacting your sps corals? And have the SPS corals been doing fine without random flow?

I have a 3 gallon at 4.5 months right now with softies and LPS but I'm looking into adding some Montipora and birdsnest. Can't find a wave maker small enough so was going to try a nano pump like you, and then was planning on large weekly water changes + smaller ones throughout the week to replenish minerals and take care of softie toxins, wondering in your experience how that would go? I am going with much lower tech, only a canister filter, heater, and light at the moment (but adding a nano pump).

Thanks for this thread, like I said it's been a great reference point for me!

Here’s a more recent pic, had some losses after adding a white cap goby and pistol shrimp from them rearranging things but it’s starting to bounce back.

Your plan for water changes sounds reasonable but I would keep an eye on parameters. I’ve found that I need to dose mg, nitrate, and Alk daily to keep things remotely stable. I test daily but am trying to do it less often. And it’s overkill but I have 6 versa pumps under the tank, 4 for dosing and 2 for auto water changes (allows me to do smaller water changes daily and makes it really easy)

 

[mpw213]