DIY CO2 System

English: (scroll down for links and video)
CO2 (Carbon dioxide) is the main source of C (Carbon) for aquatic plants, element which is the main building block of all life on Earth. Yes, you can guess it right - it is found in aboundance in natural environment like rivers, lakes, seas and oceans, but it is very rare in our aquariums with non-soil based substrates (due to rich dissolved organic carbon any additional CO2 in soil-based substrates is often unnecessery and according to Diana Walstad soil-based aquariums guru not a wise thing either.)

There are several methods already developed in aquarium hobby durring last few decades, the most obvious one is a direct CO2 gas injection from a compressed container. The most expensive one for an average aquarist, I'm afraid. Other, more "disguised" products in term of both effectiveness and price are CO2 tablets which are only (if any) good for low-light aquariums below 50-60 liters or so (avoid at any cost, which is no cost at all) and deodorant-like mini canisters with compressed CO2 and diffusor kits. Third, more recently developed method for adding carbon is in its "liquid" form (note: this is not liquid CO2 which some reffer to by mistake). More precisely, an organic compound Glutaraldehyde has a property to act as a source of bio-available carbon for most (but not all) aquatic plants. Also, it is a potent chemical that has a negative effect on some algae species. Unfortunatelly, it is not prefered or ideal source of carbon plants are used to in their evolution cycle, so adding carbon in their natural CO2 form is still best. And this will hold the truth for another millenia or so (though, I do not want to underestimate modern science).

So, I come to the point of this writing, Do-It-Yourself CO2 generator. It is the most fun and educational way to learn more about nature and your aquarium, which is the point of this hobby in the first place anyway. I have to admit now that I would be seriously tempted to buy proffessional CO2 system just because of that fascinating and fun part missing in all that "hi tech" mechanics.

Where did I start? Bellow of this writting I gave a list of all usefull articles I found on the interweb in my quest for knowledge about DIY CO2. Sorry, no re-invented hot water in this entry. But I'll describe in short how I did it with few variations (so called "improvements") + including video will be enough, I hope.

In essence, I followed this instructable with a minor variations. Instead of silicone sealing I used plastic glue gun. In my first attempt I did try silicone, but later found this solution more easier, faster and effective to seal plastic. I also plan to try no-sealant version later. As for the recipe ("juice") I used the jello version modified from countless recipes: Mix 0.5 liters of 1-day old tap water (not fresh!), 300 grams of common suggar and 1 tsp. of baking soda. Use mixer to make it compact and dissolve suggar more rapidly, then boil all to 100 degree Celsius (212 Farenheit) with a bag of gelatine powder. Let it cool for a 15-20 minutes then put it in a clean 1.5 liter plastic bottle (you can scale this for bigger bottles, I started with this one). Put the bottle in the fridge and wait for at least 12 hours to allow gelatine to compact. Be patient, trust me. Afterwards, use 0,5 liter of lukewarm water (35-45 C/95-115 F) and mix 1/4-1/2 tsp. of instant yeast (for bread baking) plus one huge tbsp. of suggar. Mix it well and put it in the bottle. Shake it well, close it well and finally deploy the system.

Few notes here: do not use fresh tap water by any means to prepare the mixture, since it is probably rich in chlorine and yeast do not like it (it is a poison for those little guys, think of it the same way as for your fish). I had an idea to add a drop of SERA AquaTan conditioner prior making, but I later pulled off from it and just used one of the pre-filled bottles I use for my home plants. There are various gelatines on the market so you'll have to experiment a bit with this part to find the best. Also, after boiling the jello mixture do not pour it immediatelly into the bottle, since it will difform its shape. Let it cool for 15-20 minutes first. Use only lukewarm water (again, not fresh tap water!) for the yeast mixture, since it will speed up production process.

Final advice: Never block CO2 injection during night with a common regulating valves, this will put your bottle, check valve or silicon hose at a huge pressure test. If you want to disable CO2 injection during the night when plants respirate CO2 and not produce oxygen, simply untwist the cap of a bottle a little just to hear the hiss sound and release the pressure build-up; twist it again first thing in the morning. I come to this idea not just because of the fish own benefit, but since diffusing CO2 in a fashion as presented in the video is a little noisy, it irritaded me at night when I go to sleep. Coincidently, untwisting the cap, releasing the pressure and letting air get in also have a benefit for the yeast: alchohol (ethanol) can evaporate and extend their life (read about aerobic and anaerobic conditions of yeast fermentation in John LeVasseu's document below).

At the end, I connected everything to an existing internal filter which acts as a diffusor (or reactor if you like, still no DIY-Splitting-Atoms here). Due simple laws of physics it is paramount to break huge CO2 bubbles into smaller ones if we want to keep as much CO2 dissolved in water as possible. As you can see from the video, it works really great. There are more good stuff about yeast and DIY CO2 system you can discover if you read some of the links below. Happy and succesifull planting!


Srpski:
CO2 (ugljen dioksid) je glavni izvor C (ugljenika), osnovnog elementa u izgradnji proteina i amino-kiselina (tkiva i organa) svih živih bića na Zemlji (izreka "sve u svemu začin C" ipak ima naučnu pozadinu). CO2 postoji u izobilju u prirodnom okruženju kao što su reke, jezera, mora i okeani, ali je prilično redak u našim akvarijumima baziranih na substratu bez zemlje ukoliko ga na neki način ne dodamo (zemlja kao podloga oslobađa dovoljne količine CO2 u procesu raspadanja organskih materija).

Postoji nekoliko metoda koji su razvijeni u akvaristici poslednjih nekoliko decenija, od kojih je najočigledniji direktno dodavanje CO2 gasa iz kompresovane boce. Na žalost, ovo je i najskuplji način jer zahteva veliko početno ulaganje (150-200 evra minimum). Drugi način su CO2 tablete koje su efikasne samo u slabo osvetljenim akvarijumima malih zapremina do 50-60 litara. Treći, skorije razvijeni metod, je dodavanje ugljenika u njegovoj tečnoj formi kao i svako drugo đubrivo za bilje (napomena: ovo nije tečni CO2 kako ga mnogi pogrešno nazivaju). Konkretno, dodaje se organsko jedinjenje Glutaraldehyde iz koga većina biljaka (mada ne sve) mogu dobiti preko potrebni element. Ova hemikalija ima i propratni nus efekat da u povećanoj dozi ima negativan efekat na pojedine vrste algi (BBA ili končasta). Ipak, ovo nije najprirodniji način snabdevanja bilja koje su tokom svog evolutivnog procesa navikle na CO2, pa je dodavanje ugljenika u njegovoj prirodnoj CO2 formi ipak poželjan metod.

Dakle, "uradi sam" CO2 reaktor poenta je čitave ove priče. Ujedno, ovo je i zanimljiv način da naučimo nešto novo o prirodi i samom akvarijumu, što je uostalom i poenta ovog hobija.

Kako sam započeo projekat? U suštini, pratio sam ova korak-po-korak uputstva, uz izvesne modifikacije, normalno. Na primer, umesto silikona koristio sam plastični pištolj za dihtovanje otvora za crevo koje izlazi iz generatora (prvobitno sam probao silikon, ali mi je potom sinula ideja o topljenoj plastici kao logičnije rešenje). Što se tiče recepta, umesto klasičnog i uobičajenog šećera, kvasca i vode koristio sam žele-varijantu iz prostog razloga jer trenutno nemam puno bilja (to će se u skorije vreme, nadam se, promeniti) i što na ovaj način ekonomičnije iskorišćavam šećer kao pogonsko gorivo. Na primer, ukoliko reakcija stane na pola puta usled prevelike količine etanola, sve što treba da uradim je da zamenim mešavinu kvasca dok nerastvoreni žele (šećer) ostaje na dnu. Takođe, ovakav miks duže traje uz ravnomerniju i sporiju reakciju oslobađanje CO2.

Recept: u pola litre vode sipati 300 gr šećera, 1 kašikicu sode bikarbone i kesicu želatina (CentroProizvod želatin se pokazao kao solidan za ovu količinu). Mikserom umutiti ovu smesu da bi se šećer i želatin brže rastopili i bolje sjedinili, potom staviti na ringlu da proključa. Prohladiti obavezno 15-20 minuta i tek onda naliti u plastičnu flašu. Obavezno sačekati, jer vrela smeša na 100 C lako istu deformiše (ja sam koristio VODA VODA, može bilo koja druga, naravno). Flašu ostaviti u frižideru da odstoji makar 12h (poželjno 24h), dok se žele ne stegne. Potom napraviti smesu pola litre vode (obavezno mlaka, 35-45 C), 1/2 kašikice instant kvasca (opet CentroProizvod) i velike kašike šećera, dobro izmešati, naliti u flašu sa zgusnutim želeom, dobro izmućkati da se ubrza reakcija, zavrnuti čep i pustiti sistem u rad. Potrebno je nekih pola sata da krenu prvi balončići, a narednih 24h da se čitav sistem stabilizuje. Pre povezivanja na akvarijum možete postaviti crevo u čašu vode da biste prekontrolisali da li sve funkcioniše kako treba. Važna napomena: ne koristiti svežu vodu (česmovaču), već isključivo odstojalu 24h za pripremu "goriva" (kao za zalivanje cveća). Kao i ribe, kvasac je osetljiv na hlor. Nosio sam se mišlju da stavim kap AquaTan-a u vodu pre pripreme, ali sam odustao.

Važan savet: Nikada ne zatvarajte dotok CO2 tokom noći uz pomoć protočnih ventila! Ovo će stvoriti enormni pritisak u flaši, što u najboljem slučaju može izbaciti sigurnosni ventil i razliti deo mešavine po sobi. Ako ne želite dodavati CO2 tokom noći, prosto odvrnite čep flaše taman toliko da oslobodite nagomilani pritisak i pustite vazduh. Na ovu ideju došao sam slučajno i to ne samo zbog zdravlja ribica, nego i zbog sebe jer me je rad difuzora tokom noći iritirao. Kao dodatna korist, otvaranjem reaktora tokom noći omogućava da nagomilani etanol ispari čime se stvara zdravija atmosfera za napredovanje kvasca i proizvodnju CO2 narednog dana.

Na videu se može videti kako to sve funkcioniše u praksi, generator sam povezao na usisni deo filter pumpe koji sada igra ulogu difuzora (tzv. CO2 reaktora). Zbog prostog zakona fizike od izuzetne je važnosti izdeliti krupne mehure na što sitnije ukoliko želimo da efikasno rastvorimo i zadržimo veće količine CO2 gasa u vodi. Na linkovima ispod možete pronaći dopunske informacije i iskustva drugih kolega akvarista. Puno sreće u uzgajanju akvarijumskog bilja!

CO2 links (English)
DIY CO2 - John LeVasseu.pdf
DIY CO2 - Tarah Nyberg.ppt
CO2 General - TheKrib.com
DIY CO2 Injection - AquaBotanic.com
DIY CO2 (Jello) - TheGab.org
DIY C02 - PlantedTank.net
DIY CO2 - Hia G. Nguyen
CO2 - Why & How To - PetFish.net

CO2 linkovi (srpski)
DIY CO2 - Akvaristika.org
DIY CO2 - Akvaristika YU
Iskustva CO2 - Aqua-art.org
DIY CO2 Difuzor - Aqua-art.org
Prskanje DIY CO2 - Aqua-art.org
Iskustva sa DIY CO2 - Aqua-art.org