Biotope One A Study of Flora and Fauna 
Dosing with pressurized CO2 provides quick uptake by the plants. The second option is as marketed by commercial products a ‘liquid carbon’ supplement in the form of glutaraldehyde. Many people opt to use a liquid based because of initial cost in setting up a pressurized CO2 tank. Some prefer simply to take a low tech approach to their tank.
Several options are available for what some commercial suppliers call liquid carbon. One of the major contenders’ product contains polycycloglutaracetal as its active ingredient. It works for what it is intended to do but works better for fighting algae. However, there are cheaper alternatives to the commercially available products and you can make them for a fraction of the cost.
Glutaraldehyde is a ‘carbon supplement substitute’ for the pressurized gas. Glutaraldehyde is available in many forms and can be bought by the gallon at a very reasonable price. Planted tanks can use the glutaraldehyde for a carbon source, but they just can’t get it as efficiently as the pressurized gas. This isn’t a lost cause, because it still gets results that are beneficial to your tank.
Dosing with glut as a liquid carbon substitute widens the gap between nice planted tanks and an algal bloom. Since glutaraldehyde functions much slower than CO2 there is more room for error than when using CO2 between your fertilization program, lighting, and other factors. It is also cheaper than setting up your planted aquarium with a solenoid, timer, regulator, tank, and diffuser system.
When dosing it is recommended to dose daily as glutaraldehyde and many commercially available name brand counterparts have an active life less than 24 hours. This is why it is recommended to dose with glutaraldehyde every day. It is also light sensitive and should be stored in a bottle or area away from sunlight so it doesn’t lose its potency.
When used as part of a planted aquarium you should also fertilize your plants and provide them with adequate lighting. Watts per gallon once was a good way to tell how much lighting needed but with modern fluorescents this method has become unreliable. Lumens per liter is a different way to look at it the same. Low light plants can grow well on 10 to 20 lumens per liter. Medium-light loving plants should be provided around 20 to 40 lumens per liter of aquarium volume. Hard to grow high light loving plants can need 40 lumens per liter or more to prosper. Without proper lighting, plant growth isn’t going to be optimal and glutaraldehyde would only combat algal outbreaks repeatedly. Plants need lights to grow well in order to outcompete algae.
Just about everything else applies when using a liquid carbon replacement program. Obviously the bigger the tank you have then you will need more lighting, fertilizer, and glutaraldehyde. It isn’t a large adjustment to make over not using pressurized CO2 for your aquarium.
Water changes are still a must do when using glut. Your fertilizer program and bioload in your tank will dictate and necessitate water changes. After doing your weekly water changes you should immediately dose again with glut. Water changes are your friend. They remove excess nutrients like fertilizer and fish waste. It’s good for your tank, so don’t think of it as wasting fertilizers when you do water changes.
A readily available source of glutaraldehyde is from Metricide 14. Metricide 14 is readily available and often can be ordered by the gallon off eBay with free shipping. When you receive your gallon of Metricide 14 it will have a small bottle of activator with is. Since Metricide isn’t being used to sterilize anything the activator is not necessary and can be discarded.
When working with any glutaraldehyde product whether it be commercially available for the aquarium hobby or not some care should be taken. Do not get it into your eyes. Keep it out of your mouth. It is recommended to wear gloves when handling the liquid to avoid skin contact.
A major commercially available aquarium product containing glutaraldehyde is 1.5% concentration. Metricide 14 is 2.6% strength and is just about twice as strong. When making your solution it needs to be appropriately diluted with water so you can make easier measurements.
If you have been using commercially available products then you may be used to dosing 5ml per 10 gallons at water changes and daily dosing at 5 ml per 50 gallons. It is pretty easy to make this solution and all you will need is reverse osmosis or distilled water, a graduated measuring container, and a dark bottle to store a liter of glutaraldehyde.
For this concentration, you will use 577 ml of 2.6% glutaraldehyde (Metricide 14) in your graduated measuring container and fill the container up to 1000 ml to make a liter of ‘carbon replacement’ glutaraldehyde. Pour this into your dark bottle to avoid contact with light and it will last longer. Now you simply just dose it like mentioned in the previous paragraph.
There were a lot of tanks and projects being maintained for Biotope One projects so an alternative had to be found for cost efficiency. This worked. It was tested on many different tanks and setups without any problems. It was a great cost-effective alternative to the commercially available products that allowed the extra money to go to plants and hardware upgrades for the propagation. Glutaraldehyde is most definitely not the same quality as pressurized carbon dioxide gas but it has benefits to a low tech planted tank.
Search around online for a good price for glutaraldehyde named Metricide 14 an order it. It is simple to mix, store, and use. There’s little reason not to use it especially if you are low tech or on a budget. It works and you will see the results with more money in your pocket for other things.
