Help... water chemistry going nuts...

[BigShot]

Ok, I got some more info on the problem I described in previous thread... I'm going crazy with this one :-(.

Here's my full tank info:

Tank is 120 gallon with 70 gallon refugium. Cheato macro in the fuge.
pH: 7.9 (Milwakee meter, calibrated).
Alkalinity: 11 (Salifert)
Ca: 490 ppm (Salifert)
Nitrates, phosphates, ammonia - undetectable. (brand new Salifert test kits).
Magnesium: 1400 (Salifert)
Temp 80.
Salinity 35 (refractometer)

Tank has been setup with brand new water, but LR and DSB from 1.5 yr old tank. Also, I've added some home made rock, made according to the GARF receipe. This rock was cured and RO water was used to make it.

Sand bed is from aragonite sand. Some clumping is visible, especially where hair alage is growing. I'm having quite bad hair algae problem, but I've ordered 200 blue hermits and they're coming in 2 days.

Other equipment:
- ASM G5 skimmer (huge!)
- Mak4 + 2 350gph powerheads hooked to wave maker
- 2x 250W 14K Hamilton HQIs
- Ozone was added at 155mg/hr for a long time, but I stopped for the past 2 weeks, ever since problem developed.

Salt (Instant Ocean) seems to be ok (normal alkalinity and Ca after dissolved).

Room is ventilated and air-conditioned. The window is opened daily when AC is not working.

There are currently no fish in the tank and has been this way for past 4 weeks as I have taken the fish out for hyposalinity treatment.

I'm using RowoPhos for phosphate removal.
RO water is used for all water needs.


Problem 1:

ORP is only at 330. It goes up when I add ozone, but as soon as I stop it drops to ~300. Also, when I stop the tank circulation even for 5min, the ORP drops quite bad. I have no idea how can it be so low with huge skimmer, strong water movement, no supplementation, no fish for past 4 weeks, AC'ed and ventilated room... ?

Problem 2:
Low pH... I have high Ca and high alkalinity. Before the alkalinity was 7. It was being depleted, while for some reason the [Ca] was increasing... I've added Seachems buffer pH (mostly sodium carbonate). The pH rose to 8.3, but went back to 7.9 after a little over a few hours...

Any idea what could be going wrong ? I.e. low ORP and low pH ?
And the quick drop in pH even after sodium carbonate?

Huge thanks,
Luke

[Randy Holmes-Farley]

ORP is only at 330. It goes up when I add ozone, but as soon as I stop it drops to ~300.

I do not believe that trying to maintain a particular ORP value is a worthwhile goal. There are just too many complications to make that desirable. Everthing that I know about ORP is in this article:

ORP and the Reef Aquarium
http://reefkeeping.com/issues/2003-12/rhf/feature/index.htm


Problem 2:
Low pH

Adding buffers is a poor way to try to control pH. It nearly always fails to control pH, and ends up with alkalinity too high. When was that pH measured?

[BigShot]

Randy, thanks for the answer, as always :-).

I will try to ignore the ORP value, but why is the pH low is still a mystery... :-( pH is measured constantly with pH meter (calibrated).
The buffer was added during daytime, the pH was measured at that time, too. That is the lights did not go off.

Thank you,
Luke

[Randy Holmes-Farley]

The pH is likely to be low (if not in error somehow) due to excess CO2 in the water. Perhaps your home has excess CO2 in it.

Try aerating a cup of water with an airstone for an hour using outside air and see if the pH rises. If it does, try the same thing with inside air to see if the tank, or the whole house has excess CO2.

These articles may help:

Solutions to pH Problems
http://www.advancedaquarist.com/issues/june2002/chem.htm

Indoor CO2 Problems
http://www.advancedaquarist.com/issues/apr2002/short.htm

[BigShot]

Randy, could the house have excess CO2 if AC is on most of the time and if it's not on, then the windows are opened ?

I'll take a look at the articles, thank you,
Luke

[Randy Holmes-Farley]

If the windows are open, then the CO2 isn't likely to be elevated much unless you are cooking with gas. Air conditioning will allow CO2 to build up.

[BigShot]

Not cooking with gas... Hmm... why would AC allow for CO2 build up ? Isn't it taking the air from outside constantly (we have central air system) ?

Thanks Randy,
Luke

[Randy Holmes-Farley]

Aid conditioners usually don't have air exchange, just heat exchange. Some models may bring in outside air, but most do not. Central air might do either, but my central air brings in no air at all.

[BigShot]

Hmmm... my central air unit is located outside, so I thought that it would bring the air from outside... is there a way to check that Randy ?

Thank you,
Luke

[thackray]

Luke,

In central air conditioning, the unit outside contains the compressor and the cooling radiator. Outside the return gas is compressed and sent in to the radiator where it cools and becomes a liquid. The liquid is sent to the “evaporator� in your attic where it evaporates in a heat exchanger cooling the indoor air which passes through the heat exchanger. No outside air is exchanged in a typical central air system. You are more likely to have an air exchange option on an “in-the-window� unit. I installed an “April Air� system in my attic when the central air was installed. It feeds into the duct work and exchanges air in a controlled way. A heating/cooling guy could tell you more about “April Air� type systems.

Phil Thackray

[BigShot]

Thanks for the info Phil... I guess I should start opening the windows more often... :-)

[thackray]

Luke,

I only noted that the typical central air conditioner does not exchange air. An indoor CO2 problem is a house to house issue which I have only read about but know nothing about. In my house (even without the “April Air� system) and running the air conditioner 24/7 I have no evidence of elevated CO2. FWIW: I never open the windows even during brief outside temperature cool downs since this lets moisture into house and paradoxically makes the air conditioning work harder when the warm temperatures follow.

Continue down the analytic path with Randy.

Phil Thackray

[BigShot]

Will do, thanks again Phil, Randy and everyone else.

Luke

[Randy Holmes-Farley]

My old house is so leaky that I have no CO2 issue either. It is mostly very new, tight homes that have the issue.

[BigShot]

That would explain... The house I live in is 2 years old... :-(
The question is what can be done to eradicate the issue. It's too hot to open the wondows in the summer and too cold in the winter :-(.

Luke

[Randy Holmes-Farley]

In the absence of fresher air, the use of limewater (no vinegar) is often the best option. Some folks also pipe outside air to a skimmer inlet.

[BigShot]

But I shouldn't add anymore Kalk as my Ca and alkalinity are much higher that they should... BTW, at what pH will the aragonite sand start dissolving?

Thanks Randy,
Luke

[Randy Holmes-Farley]

That's about the only choice. Adding slightly less limewater than the aquarium demand will allow calcium and alkalinity to fall some 9although you do not really need it to fall, it is OK where it is) and will help keep the pH from getting too low.