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Frogspawn 03-02-2007 06:16 AM

PH problem
hey guys need help with this Ph problem i have. i bought a 20g rubermaid tub from walmart last week and i put about 15g of distilled water from food lion in it. then i added 1/2cup per gallon of reefcrystals to it and then put my 100watt heater and a maxi jet 1200 PH in there to mix and airate every thing. i got thinking and tested my PH, ammo,nitrites and nitrates and phos. and all were at 0ppm. except my PH was at 8.2-8.3.
now a day later i tested only my ph to see if anything changed and it did. it went down to 7.6 mabey lower its a weird color. almost like a ornge brown (very wierd) but this always happen to me . ever since i started this SW hobby i have never had a PH of 8.2 last longer then a few hrs and thats only when i mix up a batch for a partical water change.
now i know u guys are going to say add buffers. i been that route too with my 55. i went out and bought a 2lb kent marine buffer and i slowy added that every time my PH got low. i dont want to go that route with this tank. i know its not normal to keep adding buffers every few hrs just to keep up the PH. plus when the PH fall to 7.4-7.6 and then just shoots up to 8.2-8.4 thats cant be good for the fish. :oops:
and all this happens in my rubermaid tub and my Aquarium. it dont matter where i do it. i though the LR i have and the sand would buffer it naturaly but i was wrong. i guess. i do have ha power head pointed to the top for good surface ripple
what can i do to fix this problem. and what could be causing this to happen?
thanks again guys

tecwzrd 03-02-2007 08:37 AM

7.8-8.5 is fine as long as it's stable. Adding buffers helps if alk is low but if within normal range I wouldn't mess with it.

Reef Crystals is a pretty good brand so I'd double check your 7.6 reading (which is hard to tell with AP) which is most likely off and I would check that against another brand or with your lfs. Test kits do expire as well which could be the issue.

Also its very normal for ph to be in the lower range with newer tanks and will stabilize in the higher 8.0+ range over time.

Couple of good articles on chemicals in the tank:

A Simplified Guide to the Relationship Between
Calcium, Alkalinity, Magnesium and pH

Solving Calcium and Alkalinity Problems

Chemistry and the Aquarium: What is Alkalinity?

Chemistry and the Aquarium: Calcium

roka64 03-02-2007 08:39 AM

PH comes from O2 exchange, which happens at the surface of the water. Do you have a ph pointing near the surface to cause surface ripple? Also, keep in mind pH swings between lights on/off. Make sure you measure it around the same time everyday.
That is a big swing, stability is what we want, even if the pH happens to be a little low.

Ziggy953 03-02-2007 10:05 AM

I totally agree....buffering the PH right now may be a bigger problem then a lower PH. Allow you tank to mature a bit more, like Micah said.

Kurt_Nelson 03-02-2007 10:41 AM

Somethings up, but I'm not sure what it is. Might be the air exchange thing roka mentioned, but you say it's happening in your tank too. If you have the lid on the rubbermaid on tight, that could be a problem. Also if your tank is covered tightly, that could be the problem too.

I use Reef Crystals also, with DI water. It usually mixes up to about 8.2-8.3 pH and a alkalinity of 8 dKH and will stay that way for a week until I use it for a PWC. The alkalinity might drop a bit, but not much.

tecwzrd 03-02-2007 11:01 AM

I'm thinking its closer to what Scott mentioned about measuring it at the same time for comparison purposes.

PH is highest at night just before "lights out" and lowest first thing in the morning so if it was measured first thing in the morning it could explain for the "wild swing".

Also it looks like the tank might be covered and the tub is covered which traps carbon dioxide and keeps oxygen from exchanging which will lower PH dramatically.

roka64 03-02-2007 11:08 AM

Oh yeah, good catch on the coverings, on both the tank and container.

rubikcube 03-02-2007 11:16 AM

A few notes...

1. pH isn't affected by O2 concentration.
2. pH is affected by CO2 concentration. When CO2 is dissolved in H2O, it becomes carbonic acid. This lowers the pH.
3. CO2 is absorbed during photosynthesis. Thus the longer the lights are on, the more CO2 is absorbed. The less CO2 in the water, the higher the pH.

The covering of the tub shouldn't affect the pH because there isn't any source of CO2 inside the tub. Therefore, the CO2 concentration shouldn't change when the tub is covered.

I would definitely check your alkalinity in the water change water. Otherwise, I would guess that it might be a testing error. Is it possible to verify with an LFS or some other testkit?

roka64 03-02-2007 11:34 AM

In SW, the pH is greatly effected by gas exchange. This gas exchange happens when there is surface ripple. I'm not sure I am following you on the photosynthesis part, or how it would effect premixed SW, in a covered bucket. Maybe I am just not reading it correctly.
I bet, if he took off the lid and cover, it would make a difference. At least that is how I got my pH stable (at 8.2), after I took off the lids.

tecwzrd 03-02-2007 11:49 AM


Originally Posted by rubikcube
The covering of the tub shouldn't affect the pH because there isn't any source of CO2 inside the tub.

The source of CO2 could be right in the home when mixed. If the container is covered it has nowhere to go.

Also IME a covered pwc container has consistently lowered my PH level but I'm not sure the exact causes.

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