In another thread
Alex's Nano Reef describe a school project he will do with CO2 and coral growth
I love this type of experiments because we can learn a lot from simple experiments in our living room or class room. I´m interested of this mostly because of two reasons – the impact of increased CO2 in the atmosphere for the coral reefs and how I can optimize my coral growth in my living room.
I decide to put my answer in my own build thread because I want to leave Alex thread clean and take the discussions about my thoughts here in my own thread
My set up at home is for the moment a 300 l display tank, 30 l refugium (light during nights), a DSB, a Deltec skimmer, a oxidator, a bacteria growing filter, a reactor for Al based “GFO”, a simple homemade CO2 scrubber and a Profilux computer with measurement and controlling capability. Earlier in this thread – most is described In detail.
For the moment I want to have a pH around 8.2. If I do not use a CO2 scrubber to my skimmer my pH will vary between 7.8 and 8.2 according to the number of persons in the flat and if light is on or not. If I have the scrubber connected 7/24 my pH will vary between 8.2 – 8.5 depending mostly of the light regime (photosynthesis) and in some degree of we have visitors or not. I live in a cold climate and well isolated flat.
I decide to test what happens if I run the tank with a more stable pH and a steadier concentration of CO2. I order to do that – I connected my skimmer to the pH controller of my Profilux. If pH is > 8.2 – it will not run – pH < 8.2 – the skimmer will run. The skimmers air intake goes through my CO2 scrubber. As you can see in the graph it works rather well. Some remarks: We was not at home between 28.12 and evening 30.12. By mistake, the air intake was not connected to the CO2 scrubber from morning 31.12 to morning 1.1. The media was changed morning 2.1.
Look at this graph below – it’s the CO2 concentration of my living room last week. It directly corresponding to the pH graph. The very small rise of the CO2 during late evenings of 28.12 and 29.12 is my son coming to the flat in order to take care of the cat and the aquarium. We arrived home around 8 of the 30.12, normal days – we are two persons at the flat
For me – it is still to much variation – I would love to have a steady pH level with only a variation of plus minus 0.02 and possibility to lower it during night time (in order to give my macros more CO2 – they have light from 22 in the evening to 10 o´clock in the morning.
The first thing I will test in order to achieve this is to run my skimmer 7/24 but change the air intake between the CO2 scrubber or direct from the sump cabinet (highest concentration of CO2 in the flat by average) If pH is over decided level – air from the cabinet – if pH is below decided pH – air via CO2 scrubber. I have order some equipment for this through E-bay – now I´m only waiting for delivery. If the CO2 concertation of my sump cabinet is not high enough to get the low pH I want durin nights – I consider to use CO2 gas. I have some other ideas how to use CO2 gas – maybe I can combinate this two goals.
Sincerely Lasse