Ph question

Hi Everyone.

Quick question for ya.

My tank is about 3-4 weeks old - getting out of a cycle.

I've used Distilled water to fill it up (25 gallons) and i've added around 4 of RO due to evaporation and whatnot.

My Ph is low. Probably 8 at the VERY highest. Yesterday I added 5ml of "Alkaline 8.3" by brightwell aquatics. Today I added another 5 - and my Ph isn't any different. The label says to dose a max of 5ml per day... I don't have anything living in my tank - other than sand/rock - so can I just 10ml in there tomorrow if it's still not right? What could be causing my Ph to stay low?

 

Since you have no creatures go ahead and double the dose.

Does your circulation break up the surface? If not get your pumps return pump to stir up the surface.

Also you may be having problems with low alkalinity. You need a dKH of at least 7 and closer to 10 to help with steady parameters.

If you are planning a reef parameters are more important than a fish only system.

Your magnesium may also be low and this can cause problems with keeping your pH up.

 

There is nothing wrong with a pH of 8.0, or even 7.9 if it is in the morning before, or just after the lights come on. The pH will rise through the day during the light period, and then drop again slowly after the lights go out.
Before you add any more of anything you should check to see if you really need it.
If it's not really needed then you can screw up a lot of other parameters and perhaps precipitate calcium by adding more.
If your alkalinity is 8dKH or higher then it is most likely ok and buffer is not needed.
The culprit is most likely poor gas exchange at the water's surface.
In weather where we shut our homes up, the CO2 levels rise in the home so that it makes a proper gas exchange much more difficult for the tanks.
Sometimes just adding a fan to blow on the surface, or increasing the turbulence of the surface will work, but many times, we need to get a source of fresh outdoor air to the area above the water's surface. In my case I added an HRV to my home but others have used a bathroom fan and duct to bring the air in. Maybe open a window in the room.
To see if this is the problem all you do is take a sample of the water outdoors and aerate it for at least an hour.
If the pH after aerating is .1 or more higher than before aerating, you have a gas exchange problem that will most likely make a much larger difference than just .1 in your tank over a longer period of time.

 

PH alone is almost useless as a parameter. Instead focus more on your alkalinity.

Since your tank is so young I would hesitate dosing anything until you have a couple months worth of steady water changes and testing with records to indicate trends in your chemical parameters.

 

Could you clarify just one thing for me?

I don't understand how alkalinity is separated from Ph.... If Ph is low, the water has a high acidity, if Ph is high, the water has a high alkalinity..

Where is my thinking wrong? Isn't testing Ph TESTING alkalinity?

 

VERY simply put

pH is actually a measure of hydrogen ions in the water.

Alkalanity is a measure of carbonate or bicabonate in the water.

 

not wrong

PH is a measure of the number of hydrogen ions present
Alkalinity is a measure of the buffering capacity or the ability of that volume of waters ability to compensate for a falling PH

you could have a good PH but a low Alkalinity - and what this means is that you have no buffering capacity or put another way, no insurance against acidic swings

with a decent buffering capacity AKA high Alk or DKH , your system is protected from these potential acidic swings

in easy to understand terms - consider Alk as your reserve PH buffering capacity

thats why many experience reefers test Alk and maintain Alk
and dont bother to much with PH testing - provided your Alk stays where it should do, then that should take care of your PH



Steve

 

All good info so far, I found this article helpful in understanding it though, if you want some more reading/details.
Low pH: Causes and Cures by Randy Holmes-Farley - Reefkeeping.com

 

Thanks Stevo..

one more thing to throw your way - what adverse effects could come about from having an ALK level that was too high? This supplement I ordered (KH buffer) says it will increase the Ph to no more than 8.3. Additional dosing beyond that point will only increase the alkalinity.

Thanks for your help
Brett

 

Hi Brett

one of the biggest concerns is raising anything to high to quickly
major parameter spikes should be avoided - even when the target is to improve parameters

DKH levels higher than NSW levels - some people do run DKH as high as 14 or 15
so that they are assured of that buffering capacity to protect their PH

normally 8 - 12 is the recomended range
but if your at 6 for example - you should bring it up slowly to 8 - over 3 days

you should only raise the DKH by 1 degree in any 24 hour period (many people say less than 1 degree per day)

one adverse effect of a higher DKH is that unless your SG and Magnesium are high enough to support the elevated levels, then your calcium can fall out of solution
and you can lose 20ppm calcium for evey degree of DKH you raise in your system

Steve