GH and pH Help

[Tommy4q]

Hi Guys, first time poster, hoping for some help.

I have recently set up a Marine tank but i am getting really high GH and low pH. I have no live stock and the tank has had water in it for 2 weeks

i haven't added anything apart from salt and i am using RO/DI water.

I have tested the water out of the tap ( ph 6.8, GH > 14 d )
I have tested the water in my RO water butt ( pH 6.4, GH <3 d )

then after adding salt (leaving to dissolve for 24hrs)

The water in my transport jerry cans ( pH 7.2, >21 d )
The water in my tank ( 7.4, >21 d)

i suppose my question is, should i be doing something?
i am worried there maybe something contaminating the process.

it would be wonderful if someone with a little more experience in these matters could give me some guidance.

Regards,

Tom

 

[Denbf58]

what is the salinity? do you have test kits for calcium and magnesium ? has the salt dissolved all the way? [welcome]

 

[Denbf58]

http://www.reefcentral.com/forums/showthread.php?t=2588686 check this out

 

[thegrun]

What method are you using to test your water's pH? If it is truest that low you may need to open some windows if your house to get some of the built up CO2 out of your home, although I suspect the test results are not accurate.

 

[Tommy4q]

Hello Denbf58,

Thank you for the reply. Salinity for both the tank and the transfer are at 1.023. The salt in the tank has been in there for about 2 weeks. i mixed up 25 litres and that has sat for 36hours in the jerry can

i don't have test kits for magnesium or calcium, only a broad scan for GH.

Hi thegrun

Thank you for the reply.

i am using JBL pro scan strips. Although i myself doubt the accuracy, they still have variance between individual tests. So are you thinking this is more to do with CO2, and the water hardness is none related?

Regards,

Tom

 

[DonR]

Hardness (GH) is irrelevant in saltwater. General Hardness is the measure of total calcium and magnesium ions in water, with 1 degree of general hardness equal to about 18 mg/l of calcium carbonate. Sea water would have much more than 21 degrees of GH if you measured the calcium and magnesium, expressed the values as calcium carbonate, and divided by 18. But the test kits that measure GH, including the JBL ProScan test strips, are designed for use with fresh water.

You may get a reasonable reading for KH with the JBL ProScan test strips, even though they are intended for use in fresh water. The KH (carbonate hardness, or alkalinity) should measure between 7 and 11. But if the KH results don't come out in this range, don't make any adjustments - you need to get test kits for alkalinity, calcium and magnesium before you can rely on the results.

Your pH reading of 7.4 is low but believable. However, you should not make any adjustments based on that reading, since, again, the test kit is designed for fresh water.

Don

 

[Tommy4q]

Thank you very much for this informative reply.

i am only using the JBL pro scan for indicative figures and will be getting more specific testing kits.

my KH is measuring 8. So i am going to move the jerry can into a room with good ventilation and put an air stone inside to see if i can get change in pH.

Thanks All,

Tom