Help looow pH!

[kilafaro]

pH 7.45

made some oyster crete ~ 1 yr ago - cured completely.

started tank -
salt water with instant ocean salt-

aquascaped with "dead" rocks and argonite sand.
started cyling my tank with fish food -

recalibrated my pH tester(dual stage) - reads calibration solutions accurately

SG - 1.025
pH despite through aeration 7.45.

added baking soda - not a significant change.

*Could my salt batch be "bad"/ contaminated.
*can't seed with life or coralline until pH rises.

[Randy Holmes-Farley]

Baking soda generally lowers pH, unless you bake it first. What is the alkalinity? The salt is not causing low pH. Excessive carbon dioxide is what lowers pH, and that most often comes from your air.

That pH sounds so low it may be a testing error. How did you measure it?

The best ways to raise pH are with limewater or more fresh air.

This article has more:

Low pH: Causes and Cures
http://reefkeeping.com/issues/2004-09/rhf/index.htm

[kilafaro]

measured pH with a Hanna meter - calibrated with 7/10 buffer solutions.

dosen't synthetic salt contain buffers to restore pH to saltwater levels? - says that right here on the label(lol).

My alkalinity is probably very high after adding baking soda - my test kit isn't here yet - ordered 1 week ago.

My tank is in the basement with an old gas space heater - maybe the source of my high co2? can't measure ambient co2 levels. Can't turn off the furnace - its the only thing keeping my temp at 70.

ordered calcium hydroxide to increase pH.

thankyou again,
kilafaro

[lakee911]

If your old space heater is not vented outdoors it could be a problem, but if it's vented indoors, then you stand a chance of dying from carbon monoxide poisoning.

Jason

[kilafaro]

have a co detector right next to it - it vents to the outside via a pipe attached to the main chimney.

[bertoni]

The space heater might be adding enough CO2 to the air to cause low pH. What brand of calibration buffers were used? Some are not very good:

http://www.reefkeeping.com/issues/2005-02/rhf/index.php

Also, electrical interference is a common issue with pH meters. I have to measure pH in a cup of water well away from the tank.

[Randy Holmes-Farley]

dosen't synthetic salt contain buffers to restore pH to saltwater levels? - says that right here on the label(lol).


Yes, buffer manufactures would like you to believe that too. But it is the alkalinity and ambient CO2 level that determines pH in new salt water.

calibrated with 7/10 buffer solutions.


What brand? Are they new? How recently calibrated?

[kilafaro]

I used mikwakee individual packet buffer solutions - 7/10
and a rinse solution(di water). I bought these a month ago, exp dates 9/09;9/11

calibrated last week again after the low pH readings - I'm waiting for my salifert kh/alkinity kit - but after adding the baking soda I presume its going to be very high.

loved your chemistry quiz!!! -(kicked by butt of course) but learned a quite a lot.

[Randy Holmes-Farley]

Thanks. :)

What is the alkalinity in the tank now?

[kilafaro]

sorry for the typos - I work at night - brain doesn't wake up till much later.

[Randy Holmes-Farley]

When you find out the alkalinity we can devise a plan, but limewater is likely to be the best bet. It is often used even during curing of live rock.

[kilafaro]

Finally recieved the salifert kits in the mail - tested for alkalinity and it was through the roof - my fault I had added too much baking soda in hopes of erroneously bring up the pH.

Did a 90% water change(i don't have any livestock yet) - now my measurements are as follows -

pH 8.23
ca 20
alk 4.80 meq/L

what do I do next - should I do another water change to lower my alk?

thanks again

[Randy Holmes-Farley]

What is the calcium?

No need to do anything to drop that alkalinity. It is OK.

[kilafaro]

rechecked parameters pH 8.2, kh 5.1, and calcium 20 and phos .02

haven't added any suppliments yet.

should I use recipe #1 part 1 (calcium)
without the alkalinity suppliment

thanks again

[Randy Holmes-Farley]

Calcium 20 does not make sense, unless it is some odd unit. I recommend 380-450 ppm calcium, and seawater is about 420 ppm calcium.

[kilafaro]

I haven't added any suppliments to the water yet except the baking soda initially to raise pH - have recovered from that error.
Double checked using my salifert kit - required only .04 mL to change color(syringe reads .96ml in step six).

[Randy Holmes-Farley]

That doesn't make sense. No marine aquarium ever has 20 ppm calcium. Is this salt water? What do you get on new salt mix?

[kilafaro]

You are right - I used fresh water to make my water change - I was testing calcium levels at very low salinity (sg1.010).
added enough salt to get salintiy to 1.022 now the calcium reads 250ppm. pH has dropped some from 8.2 to 7.9

summing up
kh 5.1
pH dropped from 8.2 to 7.9
calcium 250ppm
phos .02 ( i love this kit from salifert)

currently cycling tank with fish food.
will use recipe # 1 for to increase ca and alk(baked NaHco3)
will eventually plan to use limewater to top off.

thankyou again - is there any other changes you would make.

[Randy Holmes-Farley]

I'd raise the specific gravity to match NSW (1.0264 or so). That will boost calcium and alkalinity even more. Then I'd aim for the vlaues listed in this article:

Reef Aquarium Water Parameters
http://www.reefkeeping.com/issues/2004-05/rhf/index.htm