2.5L Pico Reef Concept (Lots of 3D Printing)

[Polymate3D]

Pump Update

So I have started work on the Micro controller side. This is starting with the pump, as the heater and lighting side can be done relatively easily, but the temperature detection and pump control will be more of a challenge. I am waiting on some thermistors, so thought I would start on the pump.

The current pump is 3.2 ohm and the target transistor has a current capability of 800mA. The voltage powering the entire project is 5V DC.

5V = I * 3.2ohm
I = 1.56A = 1,560mA

This is way too much. The end solution will be changing the pump to 6.4 ohm or 8 ohm. I have this one at hand however, and I also have some power resistors, so I added a 3.9 ohm power resistor in series for the time being.

This mean once the pump is modified to run without the resistor, it may be a little bit more powerful than it currently is, but I believe it has enough power regardless for the tiny 2.5L, 0.6G Pico reef.




So hopefully you can see from the video posted above that it is successfully doing both modes. Originally it had a lot of popping noise, but some filter capacitors have resolved this.

As I continue to develop the micro controller side and its functions, I will be sure to keep updating here. Away from this aspect of the project I will be attempting to gather some more accurate measurements of the container to allow me to design as tight a design lid as possible.

- Paul

 

[Polymate3D]

Heating Element

Sticking to the theme of the project, the heating element is custom made:

A 3D printed ring is made with enamelled wire used to create a set resistance. This windings surface area and resistance is made so that the maximum temperature is in a safe running region. In this original one it is around 55c. This is subject to change however.

This 1st iteration was 2.5W, but after 24 hours only managed around a 3 to 4c increase over ambient. The plan from here is to run 2x 3W elements. 1 slightly larger than the other.

These elements sit directly underneath the container, with a thermistor contacted to the container. This contact will likely be done on the back side of the container, but this will be tested in various places.

There is a few reasons for this, but the key one for now is this keeps the actual aquarium as clear from electronics as possible, keeping the limited space open to the animals going in it, and no other things detracting.

The circuit side is looking to get around to a accuracy of 0.12c, so we will be able to get fairly accurate and consistent readings. On top of this, we have 2 heating elements, meaning we can have:

Off
Low
High

Modes. The aim is the micro controller will regulate this temperature. In testing I will be capturing this data onto a SD card to help come up with the test temperature regulation control. The hope is to create a setup which learns how much to keep the heating elements on once the temperature is reached.

The micro controller will also be able to turn on and off a fan built into the lid, meaning it will regulate temperature both up and down. Something I feel is key for a Pico reef.

Still lots more to do, but its shaping up.

- Paul

 

[Polymate3D]

Pico Lid Design

So been a while since a update. As I said before, its not my core focus but a side one with many aspects to work on. Here is a look at how the lid is shaping up

The lid is broken up into 4 modules and a cross section centre section. The entire thing can be pulled off the top easily for easy access.

The 4 modules can fit into any of the 4 sections. By filling all 4 sections, the lid is sealed. These modules currently are:

1 = Pump
2 = Gravity Auto Top Top bottle
3 = Feeding / Water change access
4 = Fan cooling

The centre section will house the LED lighting. This lighting is currently targeting a 120 degree spread to enable the LEDs to mix well.

The layout and LED strength is subject to change, but the initial plan is a 1W LED in the centre, and 4 0.07W LEDs around this central one, totalling 1.28W of lighting on a 2.5L (0.7G) Pico Reef.

1W initially will be a 440nm Royal Blue LED, making up 78% of the entire power output. Then there will be 2 395nm LED's and 2 Cool Whites. The idea behind the light was to get what I need and make it as cost effective and as small as possible. I have plenty of other LEDs and can go much higher in output if needed.

The target for corals BTW is softies and maybe 1 or 2 LPS. No SPS.

Because I will be using a micro controller, these LEDs will not be set to ramp up / down, but will come on in stages.

Speaking of the micro controller, the code for it is currently around 200 lines long, but still needs various bits added to it to achieve all the plans. Off course once the code is done it will need to be run and revised until all issues are ironed out.

I may also attempt to design and get my own PCB's made for a cleaner look, so yet another thing to dive into!

I am now at the stage of starting to 3D print some of these pieces and see how they come together. The next update will likely be in the new year and will cover some changes to the pump. Don't worry, its all good!

See you in the next post, and as always, any questions / concerns, don't hesitate to mention them. - Paul

 

[Polymate3D]

Hands on with LEDs

So pretty happy with how things are shaping up with the lighting. Funds are very tight, but hoping to obtain a Seneye or find somewhere to rent a PAR meter at some stage. If I do get my hands on one, I will show some of the data.

This 1st image shows where the LEDs will be housed. The central LED is currently a 440nm LED to act as the main photosynthesis.

Other weaker LED's are 395nm here and 2 cool whites. It looks a little too blue initially to me, but I tend to lean towards white aquariums normally, and this is pushing away from that. Here is a slightly better view from the front.

In real life it does looks more white than this and with more of purple tint to it. The good news is the lid can take 5 different LED's and my circuitry can take 5x 1W LEDs if needed, but will likely be overkill. All LEDs being used currently have a 120 degree spread and the leakage out of the acrylic container is fairly minimal which is also good.

Working on the new pump and need to adjust the base for the heating elements. Got a long way to go such as PCB design, but 1st iterations will be done on breadboard and with some extra features.

Getting exciting though. All the parts needed to get the ball rolling are coming together!

- Paul

 

[Polymate3D]

Seneye Data

So I got myself a 2nd hand Seneye reef and have started using it to get some ballpark figures to see how the light is currently stacking up for my plans.

PUR was 84<86% with the 440nm LED which is the primary

66 PAR at the bottom
128 PAR at the middle
240 PAR at the top 2<3cm of water

The target is softies and some LPS so I think that hits the target nicely. There will be some lower powered 395nm LEDs to help extend down a bit and then low powered cool whites to make the aquarium not look super blue.

The way the LEDs mount is not to my liking, so I will be changing that and then taking measurements again.

Main thing is the light coverage in spectrum is good. The LEDs are 120 degrees and so coverage across just 15 x 15cm is naturally fine. The strength is also looking good.

Next step is designing the new upgraded pump into one of the modules, along with the heating elements and get some more parts 3D printed!

- Paul

 

[Polymate3D]

Pump Revisions and Project Changes

Hello. This is still in the design phase, but a few decisions have been made which have altered some plans, but lets start with a image and the pump revisions

Pump V2

This new pump runs one of my larger 3D printed loudspeaker drivers which also have a more powerful motor. This should increase the abilities of the pump. Unlike the 1st one, the driver is heavily revised to work better as a pump than a loudspeaker.

This pump utilises the piston function of the pump on both sides. The one facing down continues to use a chamber that's in contact with the water to create flow, standing waves or a mix. This driver has a large surface area and throw, allowing it with the extra power it has to shift more water.

On the other side, it now will have 2 one way valves and a pipe system. This will suck in air and then pump it into the area above the water surface. The lid will be creating a very good seal, and so this will allow a small by regulated airflow into the aquarium. All aimed at reducing evaporation.

Which leads nicely into the project changes section!

Project changes

(1) Gravity fed auto top up and fan cooling to be dropped

Doing some more research and talking to more people, it would seem evaporation is still a key concern, but in the aim of making this pico as easy and as stable as possible, I have opted to look down the Peltier and fan route to cool the aquarium in hot weather over the fan and fresh RO method.

1st reason is no RO top up needed. Uses a bit more power but the aquarium is 2.5L...so it should be too much.

2nd reason is I can regulate the cooling rate more easily with this than a fan evaporating the water.

3rd reason is that is would be a simpler system once in place. Forget RO water? no problem!

(2) Modular lid design removed

With the auto top up removed, there is less need for the modular compartments, as 2 have been removed. Macro algae was another but this could be integrated into the aquascape or a separate compartment.

By removing the modular aspect, I have create a lid with a tighter sealing design and reduce complexity.

How will the cooling be fitted?

The current plan is to have a tight sealing base with will contain the Peltier cooling side, along with the 2 heating modules. These will then be in a pocket of air which is trapped below the aquarium, leaving the may route for the heat or cooling to be transferred is through the base of the aquarium.

By using a thermistor elsewhere and comparing the time delay, or even another thermistor within the pocket of air, I should be able to create some code to more closely regulate the temperature of the aquarium. The key thing here is that we have more control over the heating and cooling of the internal volume already contained with the aquarium to keep values as stable as possible.



So that is the update for now. I am still designing the new lid and will likely need a few revisions, but the result should be better all round and with reduced material / 3D print times as well.

As always, feel free to tell me your opinion and ask questions!

- Paul