Buffer

[Danh]

hey ya,

A Buffer ive used on my 35l tank has left a white layer on the glass and the water surface. If i wipe this away with a sponge or scourer will it affect my water ?
And how do i remove the layer from the water surface ?

Thanks in advance

Dan

 

[backtotropical]

May i ask why you are using a buffer? For most tropical tanks, this would not be required.

 

[Danh]

i dont normally use buffers in any of my tanks, but i was using the 35l as a trial to see if i could keep the waters ph steady and stable through the use of buffers, but after this problem i wont be using them again.

 

[evilchild]

sorry what's a buffer? i was thinking the bit you put on a drill to make thing shiny? but the reply didn't make sence for that? sorry for being thick

 

[Jules H-T]

You're not being thick, you've just obviously never studied chemistry! Now we'll see whose being thick, when I delve back 15 years to define a buffer for you without any reference material!

A buffer is a chemical that will hold a liquid at a certain pH.

So say you want your water to be pH 6.8, but you want to add crushed coral, or limestone, or peat, to your aquarium (all of these have an impact on your pH). If you add a buffer, you can add your other material and instead of the pH changing as you would expect it to, it will hold solid at the pH the buffer defines.

However, you must beware! Buffers only work to a point, then essentially collapse.

So, in the scenario above, you have your pH 7 water, and add 10kg of limestone. Without your buffer your pH would drop over time, but with your buffer it holds steady and your fish are fine. Give it a month, and the pH would have dropped further without the buffer. Another month, and it would have dropped further were it not for your trusty buffer.

However, sooner or later the amount of pH altering substance in the water will effectively overload your buffer, it will not be able to maintain the pH any more and BANG you have a pH of 3 and all your fish are belly up. No warning, no visible change, and no slow drop in pH, it's instant.

Buffers are necessary for aquarists keeping certain fish under certain circumstances, usually because the water in their area either varies too much or is of the wrong pH all the time (i.e. fish which need either a very stable, or a certain specific, pH level that cannot be guaranteed from their water supply).

It is better to keep fish in slightly inappropriate pH conditions to be honest, as most fish will survive quite happily- it is sudden pH changes that kills fish sure as eggs is eggs. Messing about with buffers is something for the competent chemist as well as competent aquarist and should therefore generally speaking be avoided by the rest of us.

 

[evilchild]

ok that made a bit more sence than the drill. lol. and i can understand why you would want to do this to. so would you have to make a kind of sump filter with either the acid or alkile material to balance it out. i know it's more complex than but in a simple term. but i think i will stay right away from that one.

thanks for tanking the time to explain that, did a good job.

 

[Danh]

Blimey jules-h-t that was good but yeah your right, im assuming that you have studied chemistry at a good level or have just spent many hours reasearching them. I was using buffers as part of my a-level chemistry and physics courseworks.

 

[Jules H-T]

A-level Chemistry

@ evilchild: No, you don't need anything like that. All you need to do (in theory!!) is make sure you've got the right amount of buffer to contain whatever it is that is trying to change the pH. A buffer is just a liquid you add a few drops of.

A bit of basics about pH:

pH runs on a scale from 1 to 14.

1 is extremely (as in eats through glass) acidic.
14 is extremely alkaline.
7 is neutral (as you will know if you've ever seen a Dove advert). Pure water is pH 7.

If you add two things of different pH together, very simplistically speaking they average out.

If you add a litre of hideously strong acid (pH1) to a litre of hideously strong alkali (Ph14), you'll end up with 2 litres of neutral (pH7)!

If you add one to the other slowly, then the pH will slowly move along the scale. In the example of the hideous acid, if you were to start pouring in the alkali bit by bit to all the acid and measuring the pH as you go, you would see it go 1, 2, 3, 4, 5, 6, all the way to 7 as you finally add the last bit.

Buffers mess with that process, by holding the pH constant (until they can't do it any more because of all the stuff trying to change the pH).

So if you had a bit of buffer in the acid and then slowly added the alkali, it would go 1, 1, 1, 1, 5 (just used up all the buffer!), 6, 7.

Now an example of the application of a buffer:

Let's say you've got rocks that release a pH lowering compound into the water at a steady rate (which will make the water more and more acid). It's easy enough in theory- you just read how many ml of buffer you need to counteract the pH lowering. That way, you've always got lovely pH 7 water for your fish and you've not got loads of buffer.

Thing is, you then do a water change. How much of the buffer have you removed?

What is the pH of the new water going in? What if it is also lower than the pH you want (i.e. trying to drag the pH down, using up some of the buffer)? What if it is actually higher than the pH you want (effectively neutralising some of the acid from the rock, and actually freeing up some buffer to take more acid)? You'd best be measuring the pH of your tapwater every time and getting the calculator out!

Over time, the rocks will release less and less pH lowering chemicals- but how much? And therefore how much buffer do you need?

Do some more water changes with different pH tap water. How much buffer have you got left now?!

All you can do is measure the pH- but that only tells you it is still working (you are pH7).

A couple of months down the line who knows HOW much buffer is left?! Perhaps the fish are swimming in pure buffer! Perhaps you are just one tiny bit of acid compound away from a sudden dive in pH that will kill every fish you have inside 20 minutes.

It is very difficult to measure how much buffer is left without lab equipment and training.

Fish keepers only use buffers when they have no other choice. If you've got pH8 water and a fish that prefers pH6 water, you're probably going to never even notice it and nor will the fish. Like I said (most) fish can cope with pH outside their ideal without any problem. If you start trying to make the pH of your water 6 by adding acid (or even acid making rocks), with a buffer, then you'll be fine until you mess up your calculations and the buffer runs out and the pH goes from 6 to 8. Dead fishies, when all you had to do was leave it all alone.

Some fish absolutely need constant and specific pH. Until you are an advanced chemist, avoid them!