RAISING pH

[jhnrb]

Raising your Aquarium's pH Level

© Albert J. Thiel - April 1998 - Update 5

Introduction
More Information on the Dropping pH Syndrome
How can we influence the pH?
Adding buffers
A further look at the problem
Adding Kalkwasser - KW- (Limewater)
A First Step in solving this
A Second Step - Water Changes
The Goals of water changes
Additonal Steps that may be necessary

-Introduction

Not so infrequently, hobbyists struggle with a pH falling "syndrome" that can occur at any period in the lifecycle of the aquarium. Sometimes it happens when the tank is fairly "new" and sometimes it will happen to aquariums that are years old. In fact, it is not uncommon to see it happen more often in older tanks. The reasons will become clearer as you read on. It has to do with the build-up of acids of various kinds in the water.

Their pH may be too low to begin with, when they just start their aquarium, and/or it may become too low after the cycle is just completed. As the tank ages, the pH may suddenly start to take a drop and sort of go on a lower and lower sliding scale. More often than not the hobbyist is at a loss to understand why this is happening and how to deal with it.

The falling pH syndrome can "really" occur at any time in the life cycle of the aquarium. The fact is that it does happen and that many hobbyists are at a loss understanding how to counteract this chemical tendency. There is nothing unusual and nothing dangerous about this as long as you catch it soon enough and take measures to bring the pH back up. This document and others in the NetClub Library explain how to do so.

We all know that water quality varies. It varies a great deal in fact. Even water quality readings taken in the morning will not match up with readings on the water chemistry taken at night on that same tank. This is a normal occurance and results from all the chemical and biochemical processes going on in the aquarium. Note also that we do not have any control over most of these reactions.

Note also that the water quality of your raw water will vary as well depending on time of the year and your geographical location. This is not the topic of this article though. This one deals with the changes that happen to and with aquarium water. Why are there changes?

They can be attributed to various causes, many of which are not always that obvious to the hobbyist:

-You are using R.O. (reverse osmosis) water that even after the salt is added has a pH that is too low.
-You are using a D.I. (deionizer) which produces the same as above.
-You are using a combination of the above two filtration methods and end up with the same results.
-The salt you use is low in alkalinity (dKH) to begin with. It may not have enough carbonate and borate content.
-You have a high biological load. This produces lots of acidity of various kinds which lowers the buffer (dKH) and ultimately the pH.
-You overfeed the animals in your tank creating a high amount of organic waste that decomposes and results in a drop in the dKH and then the pH (as a result of acids that are produced in mineralization)
-You use chemical filtration that depletes your buffer.
-The live rock and substrate (if any), or the coral rubble and so on, in the tank do not buffer your water sufficiently and thus reduce your pH because the buffer remains too low. The buffering layer underneath the live sand is no longer buffering (this tends to happen to aquariums that have been set up for some time)
-The buffer is skewed towards the bicarbonates. This leads to a high dKH and a low pH level. Bicarbonate has a pH that is lower than what you want in your tank (e.g. baking soda typically has a pH of only 7.7-7.8)
-Your buffer may be lacking borates
-Your buffer may be lacking carbonates
-Your buffer may have too many bicarbonates.
-A combination of all of the above 3 buffer problems.

These represent quite a number of reasons why the pH may be low. The list is not exhaustive though.

Some rock or other material in the tank may be leaching bicarbonates into the water. Bicarbonates tend to pull the pH down. For example, the natural pH of sodium bicarbonate (baking soda) is 7.7-7.8 only as I indicated. If your buffer is skewed towards bicarbonates your pH will be low even though you main register a high alkalinity

-More Information on the Dropping pH Syndrom

The pH of an aquarium is an expression of the relative presence of acids and bases in ionic form. What happens is that when the amount of acidic ions (to phrase it simply) outnumbers the caustic ones, the pH of the water will be low.

The opposite is, of course also true: when their are more alkaline ions in the water than acidic ones the pH will, naturally, be higher.

Depending on which ions are more prevalent, your pH will tend to be either lower or higher.

Since it is known what affects the pH, it is possible for you to intervene and add certain compounds to the water to make the pH rise. These compounds are those portions of the buffer that have a tendency to push the pH upwards.

Carbonates and Borates will make the pH rise. Bicarbonates have a tendency to make the pH fall.

The mixture or the proportion of these compounds in relationship to the total buffering compounds (the % of each) tends to influence where the pH will stabilize itself at.

If your aquarium has lots of bicarbonates in the buffer, yet few carbonates and borates, the pH will be more influenced by the bicarbonates. As we have seen this will lead to a low pH level.

It should be obvious by now that having the correct proportions of these buffering compounds in dissolved in your water is important and is what ultimately ensures that your pH will not demonstrate a falling tendency.

Our task, therefore, as hobbyists, is to adjust the buffer in such a manner that the buffer contains all necessary compounds and that these compounds are, and remain, present in such quantities that the pH does not drop to levels lower than we wish it to be.

-Influencing the pH Level

-Adding Buffers
As the explanations above made rather clear in my opinion, a distortion in the make-up of the buffer can, and will more than likely, result in a drop of the pH level. When this is just a simple distortion, rebuffering the water with a complete buffer (one that contains all 3 compounds mentioned earlier) will re-establish your pH. Your "only" task is to add enough buffer, slowly, yes slowly and over time, until the desired pH is reached again.

You then observe the pH for a few days by testing it, and add more buffer, if necessary, until you are satisfied that the pH has stabilized itself and no longer fluctuates downwards.

Theoretically the pH should be at its lowest in the morning and should slowly rise as the day goes by, and photosynthesis takes place. Since this removes carbon dioxide from the water, the pH will have a natural tendency to rise. Towards the end of the day the pH should be higher than it was in the morning.

A further look at the problem
What was just described is the simplest of all the possible scenarios. Unfortunately, it is the one least likely to occur. More often than not, the problem is deeper rooted, and a far greater intervention on the hobbyist's part is necessary.

The low pH problem and the process associated with resolving it, is more complicated and will certainly take a longer time to solve than the one just described where only buffers are added to solve the problem.

When the pH is out of balance for several reasons, the solution is obviously much more complicated, as we shall see later in this article. Complicated is maybe not the correct word, complex is better.

When the pH is low, and is low on a continuous basis, your problem is of a totally different nature. In fact it is, more than likely, due to a combination of circumstances, each of which may require a totally different approach, or it may take a combination of methods to really solve your problem.

(CONT)

 

[jhnrb]

RAISING pH (CONT)

-Adding Kalkwasser

Sure, adding more Limewater (Kalkwasser) to the aquarium is going to raise the pH (see document on Kalkwasser), but this is only a temporary patch. Often, however, even the addition of KW (Kalkwasser) will not solve your problem. We shall see, later in this document, that the only way to truly stabilize the pH and have it maintain a healthy level, is to deal with the root cause of the problem and solve it once and for all. You need to solve your buffering problem and then go from there onwards. Kalkwasser raises the pH. There is no doubt about that, but it does so in what I would call an artificial way by adding a lot of hydroxyl ions (OH) to your water. As long as you keep adding KW (limewater) your pH will remain at a high level, even if your dKH is low. There is a caveat though, if your dKH is really low you may have to add so much Kalkwasser that it is not really possible to do so because your evaporation rate is not high enough. This would mean that you would have to remove additional amounts of water from your tank to be able to add more Kalkwasser. This is, obviously, not a viable solution. It does not make sense to have to take out water from the aquarium to be able to raise the pH but only do so artificially There has to be a better way.

-A First Step
Because the whole buffer is out of balance the first thing we need to do, if we are to hope to achieve pH stability, is to deal with this in a radical manner by undertaking a few important steps

Measure the dKH of the water and make a note of it. We need to know the number as a reference. Do not worry about what its magnitude is at this time. We will deal with bringing it to the right level later. Begin performing water changes, but read on as there is a very particular way in which this needs to be done. Perform 20 percent water changes at a time. See the next section on how to perform these water changes in the best possible manner.
One thing you need to make sure of is that the temperature of the water you are adding to the tank is the same as the one in the aquarium. This is most important.

The same applies to the temperature (this is even more important, as rapid water changes can easily bring about parasitic outbreaks - we already have one problem to deal with, the low pH and the problems with the buffer, we do not need a second one). The water changing has to be performed in a special manner which is outlined below in the next section. Not following that technique is not going to give you the kind of results we are looking for. It is important in my opinion that you do adhere to the methods described if you wish to solve your problem. I really very strongly suggest you adhere to the method I will give you. It is not complicated, but does take a little longer than a regular water change would take. Indeed several additional steps are involved in getting this process to completion.

-A Second Step - Water Changes
Changing water in the tank is going to gradually bring about the alteration of the water chemistry we are looking for to bring your buffer and your alkalinity (dKH) back in line. I have described below how to proceed to obtain success.

Start by giving the tank a real good cleaning and removing as much detritus as you can from the bottom, from the rocks, and from underneath and behind the rocks. The water that you will use needs to be treated first or pre-treated as we would call it. This involves several steps. This can be accomplished with an RO unit, a DI unit, or a combination of both. RO = reverse osmosis and DI = deionized for those not familiar with these abbreviations.

After the water has been treated it should be treated further with a silicate removing compound. If you do not, chances are you will end up with large amounts of diatoms in your tank. Use a product that is specific for the removal of silicates. Other products may remove silicates but, in my experience are not too good at doing so.

Once this has been done the water is ready for the next step. We now want to buffer this water by running it through crushed coral, or aragonite, or crushed shells, or anything that will bring its dKH up. Depending on how you do this you may need to run the water through the compound several times.

If, for instance, you use a bucket with a sieve on the top, it would be a good idea to have two buckets so you can move the sieve that contains the compound from one bucket to the other and just keep pouring the water through several times.

Now that the water has been pre-treated, silicates have been removed and buffering has taken place, it is time to add salt. Add a good quality salt and adjust the s.g. that the same one as your tank.

Next comes the temperature adjustement. You should not add water to the tank that is more than one degree Fahrenheit different than the temperature of the tank.

When all this has been taken care of you are ready for your water change. The water is now buffered correctly and has the same parameters pH and temperature and specific gravity wise as the one in the tank.
-Remove 20 % of the tank water.
-Shut off your pumps if this is necessary.
-Add the new water slowly.
-Add it to the sump if you can. If you do not have a sump, add it to the tank real slowly. This is important. You do not want to stir up too much of the detritus and calcium phosphate as well as other compounds that may still be on the rocks.

Oh, you should have cleaned the sump too after or before you cleaned the tank as, often, the sump will accumulate a lot of detritus too.

After you have performed the water change, wait about 2 hours and perform another dKH and pH test. You should perform at least 4 to 6 such water changes on consecutive days.

Note that this is going to lower your Calcium levels in the tank and that you may wish to add some compound to reincrease it. KW and other products can be used to this effect. If you need to increase the calcium level substantially, one of the two part additives (but the calcium portion only) is recommended or you can use Pure Calcium from TAT.

Keep track of how the water quality parameters change as you do each water change (applies to pH and dKH). See the next sections for how to deal with these numbers.
Various scenarios exist and we will cover them shortly.

The Goals of Water Changes
All the water changes your are performing, or have by now performed, will have affected the water chemistry in many ways.

Most importantly they will have re-established a proper balance of the buffering compounds within your tank. The proportion of bicarbonates, carbonates and borates should now be back to normal and the pH of your tank should have increased. Note that this will only happen if you use a truly complete buffer that contains all the said components. Separate additions of borate may be necessary too but that is not the case if you use a really good buffering compound

If you now start adding (dripping) Kalkwasser to your tank, you will find that the pH will rise even further. This is because calcium hydroxide, mixed with water, makes the pH go up. It is important to realize though, that KW needs to be dripped continuously and not added all at once (or certainly not as powder to the sump). You can however drip the milky KW solution into your sump or tank rather than a clear solution

How much KW needs to be added depends on the evaporation rate of your tank. If this evaporation is low, the amount of KW you are adding may not suffice and you may need to add additional calcium in some other chemical form. There are several such products available commercially.

There is the possibility that after all the water changes and even though you add KW and maybe another calcium compound, the pH still shows a slow drift and tends to go down.

This is easy to remedy. It is discussed in the next section. In most cases you will not need to resort to this, but the possibility does exist.

Additional Steps that may be necessary
We assume that you have taken care of all the water changes outlined above and have performed them all.
We also assume that you have followed the treatments recommended for the water you are using and adjusted both the salinity or specific gravity and the temperature.

If after all that the pH still shows a falling tendency, it his highly likely that you have a high bioload and that you may be overfeeding. This needs to be remedied in two ways: either you need to lower the bioload/feed less, or you need to counteract the amount of acids that are constantly being produced in your aquarium and distort the composition of your buffer.
This is done by adding borate and/or carbonates to your tank.
Another document deals with how you should do so and what you should watch for (adding sodium carbonate to the tank which is the simplest way to re-establish the balance of the buffer. Note that this procedure works in all cases but that because you cannot add lots of sodium bicarbonate art once, it is rather lengthy in most cases. Patience and persistence are needed and eventually your pH will be back where you want it to be. Ideally this is somewhere around 8.2 in the AM and 8.4 in the PM.