DI water has low PH

[adrianlau]

I recently used a freshwater PH test kit to test the DI filtered tap water and found out it is at PH 5.

After salt is added, PH goes up to 8.2 and so not a problem. But I'm using a fan to cool down my 4ft and need to top up about 1 Gal of DI water daily.

Should I buffer my top up water with PH up?

[reeftask]

dont buy the pH up. use marine buffer.

Without DI its about the same pH.

[Gouldian]

I recently used a freshwater PH test kit to test the DI filtered tap water  and found out it is at PH 5.

After salt is added, PH goes up to 8.2 and so not a problem.  But I'm using a fan to cool down my 4ft and need to top up about 1 Gal of DI water daily.

Should I buffer my top up water with PH up?

Hi bro,

D.I. water theoretically should have a pH of 7.0. However, as it sits in open air Carbon Dioxide will absorbed resulting in the formation of Carbonic Acid. Thus when water passes thru the DI unit into your pail, it will start absorbing the atmospheric Carbon Dioxide resulting in Lower pH during testing. In fact you can literally watch (on a pH monitor) the pH drop from 7.0 in D.I. water as it absorbs Carbon Dioxide.

Upon reaching a pH of ~5.5 an equilibrium will be established with the atmosphere and the pH should stabilize at around this point.

Several commercial pH meters are precise enough to measure accurately within this pH range assuming the meter is properly calibrated. However, don't worry too much if you see the pH drop in the D.I. water. If your initial readings are around 7 then drop to no lower than ~ 5.5 - you have good water.

Most reefers will measure the conductivity or total dissolved solids (tds) to ensure its "cleanliness" before re-constituition.

Re-constituition for our case means:

1) Mixing DI water with our saltmix for water change

2) Mixing DI water some form of Ca/Kh buffers for fresh water top up. I have tried Kalkwasser or Aragamight and so far am happy with the results I gotten.

HTH

[kareen]

I recently used a freshwater PH test kit to test the DI filtered tap water and found out it is at PH 5.

After salt is added, PH goes up to 8.2 and so not a problem. But I'm using a fan to cool down my 4ft and need to top up about 1 Gal of DI water daily.

Should I buffer my top up water with PH up?

think of it this way... the amount of top up volume verses the tank volume... how do they compare in term of ratio.... The only way it is possible to lower the tank ph is thru' long term no water change and additives.