Lowering PH - Planted Tank Mates
PH Scale

Lowering PH


Lowering the PH and modifying your aquarium parameters can be tricky.  Many water conditions noted on websites, including Planted Tank Mates, are general guidelines for you to understand and target.  Constantly modifying and trying to hit specific water parameters can do more harm if it’s already loaded with livestock. Unless you have a very demanding species, most can adapt to the water conditions as long as it does not change too dramatically.  Ideally, you would have established the tank and routine maintenance before adding in livestock, but things always change.  

What is PH and its role?

PH stands for Power of Hydrogen.  It’s a general way of measuring how acidic or alkaline your water is.  It’s also a unit of measurement that identifies the water parameter necessary for a specific fish, invertebrate or plant species.  You’ve probably seen many test strips which show a PH range of 0-14, 0 being Acidic, 7 being neutral and 14 being alkaline.  If you plan to keep Caridina shrimp, you’ll notice that they prefer more soft and acidic water conditions from about 6.6 – 7 PH.  Neocaridina shrimp on the other hand, prefer more alkaline conditions ranging from 7.2 – 8 PH, however, they’re relatively hardy and can adapt to softer conditions as well.

PH Scale
PH Scale – Test available on Amazon

What is GH and KH

GH is General Hardness.  It’s the amount of minerals, specifically calcium and magnesium, that’s been dissolved in your water.  All plants and livestock need minerals and some amount of water hardness.  These minerals can typically be found in tap water or directly added with additives such as Seachem Equilibrium.  Sometimes, hardscapes such as limestone or crushed coral also help increase GH.  Excessive levels of GH can sometimes be indicated by white limescale at the rim of your tank.  General hardness does NOT have any direct impact on PH.  

KH, carbonate hardness, on the other hand has a direct relationship to PH.  A high KH says that your PH is stable and less likely to fluctuate.  Large swings in PH can harm livestock and plants, so KH helps keep these swings slow and steady.  Increasing your KH directly parallels increasing your PH, the two go hand in hand.  Seachem Alkaline buffers help raise KH and have formulated doses to minimize drastic changes.  Baking soda is also an alternative, but like all additive solutions it has to become routine.  Additives cannot be a one and done deal; it has to be monitored and incorporated into your water changes regularly.

GH KH Test Kit
GH KH Test Kit – Available on Amazon

How to lower PH

There are several ways to adjust high PH in established aquariums.

    1. Mix your water.  If you’re doing water changes solely with tap water, try incorporating a mix of RO or distilled water to help balance it out.  It can be a bit of trial and error, but do several PH tests with some parts of tap + RO or distilled water in a bucket until you find that right balance.  When you’re ready, remember not to do dramatic water changes; slow and steady through the course of days and weeks is best.
    2. For shrimp tanks, try adding Indian almond leaves, cholla wood or alder cones.  It’s a natural way of lowering PH and shrimps love to munch on them.  It does release a lot of tannins which results in the yellow-brown murky water.  You can pre-soak them in a cup for several days in advance to reduce this. There’s no harm in adding this to fish only tanks as well.
      Lowering PH
      Alder Cones, Cholla Wood, Indian Almond Leaves – available on Amazon


      3. Liquid additives such as API PH Down is another option.  This is last on the list and comes with a word of caution.  It’s a short-term solution and can be deadly if overdosed.  If you’re proceeding down this route, do small tests and monitor your livestock.  Keep a log, test PH often and find a steady routine.

All Things Considered

Stability is key and is often more important than trying to obtain the perfect parameters.  Whatever method you decide, remember that it’s a trial and error process; a very slow and gradual one.  You may also notice that your PH swings naturally between daytime and night.  For those with CO2 in their tanks, the PH is lowest during late afternoon when the lights have been on and plants have been photosynthesizing.  In the early mornings, the PH has increased because the lights have been out and plants have been going through respiration.  This natural phenomenon is small enough that it does not harm livestock, but is a factor to consider when you’re adjusting your PH.  Consider the time of day you’re testing, when you’re making changes, and when you’re testing again.  Remember the triple “S” to any change you make.  Slow, Steady and Stable.

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