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Aquaponic Nutrients to use instead of Salt

Using salt in aquaponics is not a new thing but here is a few very handy ideas for your system should you need them.  I have written about Salt in Aquaponics.  In this previous article I offer a calculator for working out how much to use in the event of a Nitrite issue with your fish.  In this article I want to share some other ways to protect your fish which are also aquaponic nutrients so your plants also benefit! The primary reason for adding salt (Sodium Chloride) is to prevent your fish from being poisoned by Nitrite and as a general system tonic to keep the bacteria you don’t want at bay.  Provided you have set your system up well, it will be rare that you will need to use salt.  Majority of the time it is used during start up of a new system, during cycling to protect the fish. Believe it or not salt (sodium) is very important to fresh water fish and assists with osmoregulation and transfers of wastes from the gills into the water through a very cool little thing called a Sodium-Potassium Pump.    We even have them.  If the pump is not working properly then the toxic wastes (ammonia) will build up and next thing you know we are all not feeling so grand.  Anyway, if you are interested use your googlnator to check it out.  For now all you need to know is it is important. But what about Chloride or more to the point Chlorine? (no don’t run off and grab your pool Chlorine ready for treatment)… It is Chloride that does the work protecting your fish from Nitrite poisoning and to a lesser degree can help with general system health.  However, there is a dark side, too much sodium can be bad for plants.  Too much sodium definitely is and to a lesser extent Chloride. With that in mind, I want to jump into just a little chemistry.  Yes I can see you nodding off.  No really it is not that difficult! so say with me. If Chloride is what protects our fish from nitrite then it makes perfect sense that any other compound containing Chloride will do the same job which double as aquaponic nutrients for your plants.  Seeing how we don’t really want that much Sodium in our system, lets investigate some other goodies we can use as alternatives that will benefit our plants too. What you need to know:  For every 1mg of Nitrite in your testing you will need at least 10mg of Chloride for it to be an effective protection against Nitrite. Lets take a peek at some basic metal halides… This dynamic periodic table may come in handy for those that want to work it out from scratch with any chloride compound I have not mentioned.  The beauty of using these Chloride compounds is they will not accumulate like Sodium Chloride as they will be used by your plants. Same as the salt calculator, multiply your nitrite reading by 10, then multiply that by the volume of water and divide that by the Chloride (Chlorine) percentage.  That will give you the milligrams treatment.  Divide by 1000 to get your grams treatment or divide the mg by 0.000035274 to get ounces. [heading] Fantastic aquaponic nutrients and treat your fish [/heading] Potassium Chloride (KCl) This is really easy to get and a great source of potassium for your fruiting plants.  You can make this if you are really careful by mixing hydrochloric acid and potash (potassium hydroxide) though you are best just to buy it pure and ready to go.  It’s use much like salt will not affect your pH. This little gem has one atom of each compound Potassium and Chlorine so very easy to work out how much you need.   The Chlorine content is 35.45, the Potassium is 39.0983, so the molecular weight of pure KCl is 74.5483. (check the table).  Super if we divide the Chlorine weight by  the total weight of the KCl we will get a percentage of 47.61%.  So you would divide your result by 0.4761. Hydrogen Chloride (HCl) or Hydrochloric acid This is handy to use should your pH be a little high and you want to bring it down during a nitrite spike event.  Generally a Nitrite spike will more than likely also have an ammonia spike as well so it can be a good idea to lower the pH.  However, not a good idea to change up the pH of the water if your fish are already stressed. I would stress use with caution.  HCl has one atom of each like KCl so easy to work out how much to use.  See the table, Hydrogen weighs in at 1.008 (1 will usually do) and again Chloride (Chlorine) weighs 35.45 with a total weight of 36.458.  Again divide the Chlorine weight by the total weight gives you 97.24%.  Pretty effective stuff huh?  So divide your nitrite result (x 10) by 0.9724.  You are not going to need much of this one.  Important: check solutions strength. Magnesium Chloride (MgCl2) Have a magnesium deficiency and nitrite issue at once?  What are the chances?…  MgCl2 has a neutral pH but should the pH of your water be higher or lower than 7 it will have a slight effect on the ph.  Though in the quantities you will be using it will not vary much. This compound is a little different to the ones above in that it has 2 atoms of Chloride.   So the weight of Magnesium on the periodic table is 24.305 and we know Chlorine is 35.45 but now we have two of them.  This will make the total weight 95.205.  When we divide the Chlorine content by the total weight we get a percentage of 74.47%.  Now we divide the nitrite (x 10) by 0.7447 to get how much we should use. Calcium Chloride (CaCl2) Great for calcium deficiencies but be very careful with this one.  It has an exothermic reaction in water (it gets hot!).  It has a pH of about 7.8 so it will raise your pH slightly but again because of the 2 atoms of Chlorine you will not use much of this and it is a very efficient way to add calcium quickly to any aquaponic system. With the two atoms of Chloride it has a total weight of 110.978 with calcium at 40.078 and 2 x Chloride at 70.9.  Dividing the Chloride by the total weight you will end up with a Chloride concentration of 63.887 so divide your nitrate (x 10) by 0.6387 Note on concentration of compounds Not all things are equal in chemistry in so much as what we can purchase.  For example hydrochloric acid can be bought with a concentration of 28 to 35%.  This percentage means the compound is not pure so you will have to divide your result by the percentage as a decimal point eg: 35% is 0.35. Example if our calculation says we need to use 100 grams of HCl, we would divide that result by 0.35 to get the true amount we need.  This would mean our 100 grams of HCl would change to 286 grams.  I will put together and updated calculator for those that tire of the word Chloride… Final note I have read some interesting misinterpretations of chloride use in aquaponics, some of it relating to the use of hydroxides and oxides and chlorides…they are very wrong.  If you are wondering if you are going to harm your plants with the addition of Chlorides, this article shows the tolerances of most plants between 350mg/L to 2800mg/L which is far higher than you will ever add with these compounds. I will put together and updated calculator for those that tire of the word Chloride… Subscribe to stay in touch click here Regards Paul…

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