Sulawesi Mineral 7.5 and PH

[JohnH]

I've been using Sulawesi Mineral 7.5 to raise the TDS of my tanks to around 200 ppm. I noticed that the PH of my tanks started to rise, but went above PH 7.5 that Sulawesi is supposed to buffer to.

My 3' tank with inert gravel as substrate is reading a PH of 8.2

My divided tank with ADA Amazonia reads a PH of 7.2

My new rack with inert gravel reads a PH of 8.2

So I did a test with three buckets of RO water:

• Bucket 1 - RO Water only
  
  • TDS - 1
    
  • PH 7.0
    
    
    
  • Bucket 2 - RO water and inert gravel I have in two of my tanks
    
    • TDS -14
      
    • PH 6.8
      

    [*]Bucket 3 RO Water + Sulawesi

  • TDS - 221
    
  • PH - 9.4
    
    
    
    
    
    Is what I am seeing normal? I thought Sulawesi would buffer the PH to 7.5?

[Dean]

Good to see you testing different variables.

1st problem is your measuring TDS and not EC as the manufacturer recommends on the bottle.

To get ph 7.5 your EC reading should be 270 +-40 (magine of error in most Pens)

If you follow the instructions correctly you will not have the problem of high PH ;)

All the saltyshrimp minerals are measured with an EC pen, NOT TDS.

Forget trying to convert from tds to ec also as tds is measuring organics also!!!

[JohnH]

Yikes, so I need an EC pen?

One like this? http://www.ebay.com.au/itm/NEW-DIGITAL-EC-PEN-METER-TESTER-HYDROPONIC-GREENHOUSE-/190711363209?pt=AU_Seed_Starting_Hydroponics&hash=item2c67487689

[Dean]

yes but some things are cheap for a reason :)

This is the one i use and have had zero problems with.

http://www.easymeters.com/cart/product.php?productid=646&cat=0&page=1

They sell in Australia for $97 lol

[JohnH]

Did yours come with the calibration solution?

[Dean]

no i purchased it. but it has not needed calibrating since i got it.

I keep the EC and PH pen in storage solution 24/7 so there is never a problem :)

[BlueBolts]

I keep the EC and PH pen in storage solution 24/7 so there is never a problem :)

I was just about to type a thread about that ! Thanks Dean for reading my mind ....

[JohnH]

Must get me some storage solution too.

[ineke]

What is the storage solution? I have just purchased ph and ec pen haven't received them yet.

[Squiggle]

Just waiting for my EC pen too, might look into getting the storage solution too :encouragement: