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2.5 Pico Bonsai Reef

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Tank Specs:


Current Tank age: 5 months

Display: 2.5 gallon 1" thick cast acrylic tank.

Dimensions: 11” tall, 8" x 6” Display area ~ 2 gallon 4"x4.5" back filter area ~ 0.5 gallon.

Lighting: Kessil A80 Tuna Blue

Lighting Schedule: 6:30am-8pm
Lid: 1/8 acrylic.

Heater: Cobalt Aquatics Mini therm 10 watt heater

Return Pump: Rio 180 Plus 120g/hr
Filter: Aqueon Quietflow Internal Power Filter AT10 (Filter Floss, Boyd Chemi-Pure Blue Nano Pack inside),  MarinePure Bio Block (1"x4"), 3 PC 1" Ceramic cube, 3 PC 1" Ceramic filter ring, Small Chaeto

Controller: Apex Jr, TE-48-20 Thermometric(Peltier) PID Controller

Chiller:  Custom DIY Iceprobe 120W type thermometric Chiller with Noctua NH-U9S, Premium CPU Cooler.  Super quiet and efficient comparing to original Iceprobe

Rock: 1 Piece ceramic VidaRock Bonsai

Sand: Natures Ocean Samoa Pink

Salt Mix: Tropic Marin Pro Reef Sea Salt mixed to 1.026.

Glass Cleaner: Mr. Clean Magic Sponge,  toothbrush.

AWC: 2x Kamoer X1 Single Doser (500ml per day ~ 5% total WC)



  • Daily: Feed tank, clear display area if needed, manual top off (every little maybe 15ml water and close to zero during winter), Automatic 5% water change
  • Semi Monthly: Change filter floss
  • Monthly: Make new batch of 5 gallon saltwater, change Chemi-Pure Blue pack, trim off 50% of the Chaeto, Rinse off marinepure bio block, Siphons out back chamber debris. 
  • 2 Months: Clean return pump.



Live Stocks


  • Orange Guttatus Birdsnest
  • Green Long Polyp Galaxea
  • Purple Star Polyp
  • Green Candy
  • Green Torch
  • Red and Green War
  • Sunny D Zoa (I think) 



  • 1 Mini Carpet Anemone
  • 1 Pom Pom Crab
  • 1 Pederson's Cleaner Shrimp
  • 3x Sexy Shrimp (1 male, 2 female)
  • 2x Nassarius Snail
  • 1 Bumble Bee Snail



  • 1 Red Neon Eviota Goby
  • 1 Two Spot Bimaculatus Blenny


About Tank:

This tank was originally designed and custom made for Jim (Well know tank in here) for his PICO cold water reef.  I purchased over a year ago to start my own when he shut it down.  It been sitting in my garage forever before I got started on the project.  By the time I finish all the mod ColdWater Co. was close and pretty much no where or hard to find any store that sell cold water live stock.   Now of the mods my idea was to keep this tank as maintain free as possible.  For a pico tank I believe two of the hardest thing are salinity and chemistry.  An auto water change should take care of the chemistry.  For salinity my thinking was if I can control the evaporation it should take care of the salinity.  For evaporation control keep to low wattage equipment, a will insulated tank, and a stable temp was important.  


Temperature is controlled by mod Iceprobe.  I pretty much dump all the original Iceprobe stuff with the exception of the AL probe block.  I want to get a custom CNC Cold block as I don't think a solid round block is the best way to transfer the temperature, but the quote for a local prototyping shop was out of the earth for a single piece run.  Other are I find the Iceprobe was too noise as it use a cheap fan and the heat sink was too ineffective.  The original iceprobe was only 60w but the heat sink side was burning hot to the touch when it ran.  FYI peltier module have two side one is cold one is hot the module itself is only couple mm thin so hot side will travel to cold and cold to hot by default.  To make it the maximum effective the hot side must be cool as much as possible.  By using a high performance heat sink and fan my new modded iceprobe heat sink is only warm to the touch and I'm running a 120w peltier double the power.  The PID controller will auto ramp and power up and down as needed to control the set temp (my set at 25.2 C ~ 77.2 F).  I think about 90% of the time it was only ramping around  25%ish power once it got to the set temp and during high noon (we don't run AC when no one is home) it ramp up to 50% to100% power once awhile.  Took me couple hours to get enough data to fine tune the PID system once it was tuned its able to maintain an temp of 25.2 C +_0.1 C all day long. (I have to work with C as the controller only have C these controller are mainly made for lab and med industry).  Btw these controller are a little expensive anywhere couple hundred to couple thousand (Thorlab) depend on the wattage it need to control and the temp control tolerance.   This model have tolerance of 0.1C which is more than enough for reef tank.  I pick my up on ebay off one of those med equipment surplus dealer for only $40 it was sold as is untested or even try power it on, but i figure just a frag cost not much to loss.


Filtration with only a 4" x 4" x 7" area there wasn't much room to work.  However i was able to fit a AT10 filter (with filter floss and a pack of nano Chemi-Pure stuff inside),  a 1"x 4" small marinepure bio block inside a fine mesh bag (this way I can easily take out for rinsing without damaging the block.  If you don't know Marinepure block does get fragile overtime in the water) , I even throw in some 1" ceramic cube and ring where ever I can.  I even throw in a small Chaeto ball on the top side.  The chaeto was original just for fun and play during the initial cycle, but it grown 2x the size within 2 weeks during the initial cycle.  Now it still grow but slower about 2x the size per month.  There is no dedicated lighting for the chaeto it just pick up light off the Kessil A80.   There an layer of removable thin plastic mesh between the chaeto and button part of the chamber to prevent chaeto from getting into the return pump or grow around the temp probe or bio block. 


Future Plans:

LivestockNot for awhile I  was to wait to see how the coral separate first


Equipment Mod:

  • Change out RIO 180 return AC pump to a DC pump 
  • Change out the AT10 filter to a DIY filter also powered by mini DC pump
  • Change out Cobalt heater to a DC heat pad.
  • Change out apex jr controller to a DIY raspberry PI zero control.
  • Once the entire system is convert to a safe low DC power equipment all cord will be cut and combine to a single mulit pin power cord.  Goal is to aim a truly plug and play pico system.  Single power cord in with 1 single signal wire out (temp probe, pwm control, etc wires) with an pico size control at the front.


















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how are the fish doing in such a small space? I'm guessing your filtration is extreme to counter the high bioload?


also, any issues with coral growing on the bonzai with shadows cast on the lower branches but the upper branches?

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Those two fishs are tiny about 1" long and fully grown one of the sexy shrimp is bigger than them haha.  Their seen doing pretty good.  As for coral no sure yet which why I want to wait.   It going to be an trial and error process on which coral will work or not.  I'm pretty sure the purple star polyp will be no issue and since its one piece rock I can take it out for trimming to control it.  I'm also considering taking out the sand and put gsp on the bottom and let it grow so it look like green grass surrounding a tree.

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I like the GSP idea!!! probably best to put small frags side by side in a circle so they grow outwards, rather than one or two chunks as you don't know what they'll do.

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I would like to see that raspberry pi controller when you are done. Sounds awsome

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