Nutrient control | D-D The Aquarium Solution
Hi Tony
I’m just after some advice on nutrient control. At present I’m running an Algae Light reactor with Cheato but finding my nitrates are still high, over 20. I run RowaPhos in a reactor which is currently 0.4. I’m not getting a great deal of growth on the cheato and want to bring my nitrates down. I’m considering running the D-D Bio pellets in a reactor or possibly the Deltect Nitrate reactor. I’ve ran Bio pellets in the past and had some success. I’ve never used a nitrate reactor though. Just wanted some advice on what the best option for maintaining nutrient control on my 650 litre tank would be? Thanks, Ashley.
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Dear Ashley
As you know Nutrient control isn’t an exact science, two aquariums can be set up identically for instance but show two very different nutrient results.It can take time and experimentation to fine tune a particular system to run low nutrients.
If we take the most common reasons for poor nutrient management from a biological stand point we must first make sure that following basic points are scrutinised and if required amendments made.
1. Stocking levels. As reef keepers we love fish but we also have to be mindful that heavy stocking will nutrient load a system, by heavy stocking we don’t always refer too ’too many ‘ fish but the number of tangs of other messy fish that if well fed will potentially push a reef tank towards high nutrient loads.As a general rule one can usually stock a higher number of small shoaling fish by weight than messy fish and still maintain lower nutrients as large fish tend to require heavier feedings of bulkier nutrient rich foods. So as I say keep stocking in mind.
2. Feedings - Im a great believer in feeding little and often, feeding heavily with nutrient rich foods once or twice a day will often equate to waste , poor digestion and nutrient issues, little and often will allow all food to be eaten in one sitting and allow the fish to digest the foods completely. This is especially relevant to tangs as they have a relatively small gut designed for constant grazing and will tend to expel heavy feeds without digesting them well.
3. Flow and aquascape - Make sure you have adequate flow around the rocks and that the aquascape is open enough to keep detritus flushed.
4. Sand beds - One of the fastest ways to increase nutrients within an aquarium would be to install a sand bed that’s either too deep or too course , deeper sand beds ( sand beds that are not designed to be proper deep sand beds ) , that are usually deeper than 1” or use very coarse sand ( 3-5mm grains ) tend to become nutrient sinks over time and will eventually push nutrients up to levels that cannot be naturally controlled by correct stocking ,feeding, aquascape design etc etc. I have experienced hobbyists that have witnessed a huge drop in nutrients by slowly removing sand beds that they have been unwilling to remove previously as they were adamant that sand couldn’t cause nutrient issues. I personally only ever run a smattering of sand, for the last few years I haven’t run a sand bed at all and the tank and SPS look better for it.
So what can be done if all above is in check but one still struggles.
1. Double and triple check the test kit results with other known good kits to save you chasing your tail 
2. If using Cheato try and get you PO4 down under 0.08 ppm, , preferably 0.02-0.04ppm . Cheato generally wont grow well in high PO4 , once you get the PO4 down it will start to grow and help keep PO4 from rising again.Equally for Cheato to have a big impact you will need quite a large algae bed, whilst the Cheato reactors are a neat design they probably don’t have the real estate for proper algae based nutrient control but they are better than nothing.
3.Bio- Pellets , Pellet systems can be a great way of reducing Nitrate and a little PO4 , you will need to keep in mind that the bacteria that will grow on the surface of the pellets that consume the Nitrate will need to be happy and have access to Nitrate and a small amount of PO4 for cell production. If the Nitrate to PO4 balance is off the bacteria may not grow in enough numbers to make a dent.
4. Nitrate reactors - Nitrate reactors work in a similar way to pellets in that the bacteria are provided with a carbon source, in this case Ethanol or Methanol ( Electron Donor ) , Nitrate ( Electron acceptor ) and a background level of PO4 ( used by the bacteria for respiration and to produce ATP which is a form of biochemical energy  ) . Nitrate reactors have the benefit of being able to be tuned for use , in other words you can increase or decrease the dose of Ethanol to suit requirements and also the amount of effluent the reactor produces a day. Pellet system are pretty much unregulated with regards to fine control and are far easier to set up , Nitrate reactors have much better control to allow fine tuning of nutrients although one must understand that the level of user input and understanding will also increase to enable you to reap those rewards.
5. Water changes, this will only go so far, you will always be diluting your nutrient values and not making much of a dent, a 20% water change may only see your Nitrate drop around 4ppm for instance and you will probably be back to 20ppm within a few days. If you change higher percentages of water by ratio you risk destabilising the tank chemistry and microbiology so no real up sides as far as nutrient control.
I hope this helps Tony