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Common Aquaponic Problem – Simple Fix

One of the most common aquaponic problem, also seen in aquaculture systems, is elevated ammonia.  You may notice persistent ammonia levels in your testing but can not figure out why your fish appear just fine. You many start to panic and stop feeding, do water changes and your enjoyable hobby starts to become stressful.  This is what the common aquaponic problem is and how to fix it [heading] Common Aquaponic Problem – High Ammonia and low pH [/heading] Often persistent high levels of ammonia happen when you first start a new aquaponic or aquaculture system.  However, it can happen at any time especially when you do not pay particular attention to your pH. Generally in aquaculture systems you wont see this issue as much as you will with an aquaponic system because aquaculture tend to keep a pH in the higher level of 7.2 to 7.4. Where as aquaponics systems like to run a pH lower than 7 and often down as low as 6.5.  This is a great pH for the plants to keep the majority of the nutrients free for the plants to use, but it can be a very slippery slop and the pH can drop rapidly.  Even overnight. At these low pH levels the ammonia is not very toxic to the fish and often safe for the fish up to 4mg/L.  I have seen as high as 8mg/L though I would not recommend this at any pH. So what’s the common aquaponic problem here? Low pH (<6.5) can be very difficult to maintain and one of the mistakes commonly made is to use the colormetric (titration) test kit and read a pH of 6.   Your ammonia is high, no nitrite and your fish are fine…. for now. All of the low range pH test kits will only read to a low level of 6 (it will turn a pale yellow)…. but…. Your pH is more than likely much lower than 6 but you have no way of testing lower readings without a digital pen.[note style=”” bg=”” border=”” bordercolor=”” color=””] Note: pH lower than 6 will compromise the fish immune system and strip off their protective mucus coating leaving them exposed to disease infection and they will not handle well. [/note]While your nitrifying bacteria will acclimate or become accustomed to most pH ranges, as the pH gets lower than 6 you will find the Alkaliniity in your system is very much gone!  Here in lays the common aquaponic problem! You wonderful bacteria converting your ammonia to nitrite and nitrate effectively run out of carbon.  While they can grab some carbon (bread) for their nitrogen (ammonia) sandwich from CO2, they need more than the fish are producing. With that the CO2 in the water is only relative to the alkalinity and the pH.  So you get a double smack because CO2 in the air is very low (0.035%) and nearly all of the CO2 in the system is produced by the fish and will gas-off not giving your ammonia munching bacteria a shot at it.  Secondly at low alkalinity and pH there is virtually no CO2 in the water. [heading] How to Fix ths Common Aquaponic Problem [/heading] Quite simply increase your alkalinity…. But… it is not as easy as throwing in some bicarbonate, oxide or hydroxide because with the elevated ammonia when you increase the alkalinity you will also increase your pH.  Increase the pH above 6.5 with high ammonia and your fish will die…. Not to fear! Take your time.  Add 50 grams of calcium hydroxide (builders lime) to 1000 liters of water each day.  Closely monitor both your pH and Ammonia as you increase the pH to 6.5.  You can do this even slower if you like.  Always make small changes and do not be in a rush! You will quickly see the ammonia start to drop off, but because your biofiltration has effectively collapsed, you will have to watch for the nitrite spike.  Add 0.5 grams of pool salt per 1 liter of water to prevent any issues with the sudden increase of Nitrite. To summarize: Test your pH often.   Some say, they never test their system.  Don’t fall for that. Consistantly add an oxide, bicarbonate or hydroxide to maintain a pH of 6.5 If the ammonia is persistent follow the above steps. Prevention is much better than the cure.  So test often and adjust as needed and your system will remain healthy and functional. After you have reviewed the above links, I want you to share your experience when this has happened to you and what you have done in the comments below….

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