Another Person Puzzled by pH

[dfox]

My 55 gal tank has been up and running for about 2.5 months now. I've learned a lot from reading these message boards, but I still haven't been able to figure out why my pH is low. It generally varies between 7.95 and 8.10. Typically it is 8.00 or 8.05. I use the pH Checker by Hanna to test. I've calibrated it. Also used Aquarium Pham drops to test.
Here's the general specs of my setup: 55 gal tank, 50 lbs LR, less than 1 inch cc substrate, Penguin 200 HOB filter, Prizm Deluxe Skimmer, 2 powerheads (total about 350 gph), 2 heaters, about 100w light total (40w actinic, 40w 10K, 15w 18K, 15w 6700) run for 11 hours per day. I feed pretty heavily once per day, usually frozen brine shrimp, krill, or flakes.
Inhabitants are: 1 yellowtail damsel, 1 bicolor blenny, 1 cleaner shrimp, about 10 various crabs, about 10 various snails, 1 brittle star. All seem fine right now.
Water parameters are: 0 am, 0 nitrite, 0 nitrate, 440 calc, 9 dKH, 1.022-1.023 SG, 80 degrees. 10% water changes weekly. Supplement calcium, iodine occasionally. Polyfilter sometimes, change carbon every week or two. I do vacuum the cc on water changes.
I've tried increasing the surface agitation. I try to keep my calc and dKH in good ranges.
What else can I try? Or should I not worry about it? Thanks.

 

[mcsd22]

In my opinion anytime the ph is below 8.0 its time to worry. Using deionized water will help and keeping an eye on ak would be good. Keep the calcium level up also.

 

[dfox]

Thanks.
I use only DI water for weekly water changes. I did use conditioned tap water for the original setup 2.5 months ago. This is the reason for the polyfilters - to try to make sure no phosphate was left.
My KH is ~160 ppm according to Aquarium Pharm test kit. Does that sound about right? Calcium is very steady, and has been gradually increasing from 380-440 over the past month as I have been supplementing.

 

[mcsd22]

The tap water was the cause of the low ph to start I would say. You got to watch the distilled water too because some of them are almost as bad as tap. You really should be using de- ionized water from a ro filter. They range in price but you can get a small 1 for about 50 dollars that has changeable cartridges. Your ph will then start coming up. Remember no drastic changes in ph allowed and never drop below 8.0 or bad things will start to happen.

 

[92protruck]

you must have ran across my old posts. I too was concerned about low pH. I bought the pinpoint monitor and mine also goes from 7.85 in the a.m. to 8.10 in the p.m. I tried all the same things as you and my levels are fine also. I was told don't worry about it. I thought it had something to do with the RO/DI water I used to start the tank and do freshwater topoffs with (although the experts on here say no way). My RO/DI is 6.0. I started the tank with that and it gets a 1 1/2 gal. of 6.0 pH topoff everyday. I just figured that has to have some ever so slight effect on overall pH. I am now leaning towards what is suggested in Fenner's book, that the alkaline reserve that you started with will get nicked away over time and your pH will drop without the use of chemical additives or buffers. But everyone on here says never add a buffer...find out why its low and fix it! Well....I think its low because over time the alkaline reserve...........etc. So do you add a buffer or not? I haven't yet. I disagree with the other post that says anything below 8.0 is when bad things happen. A number of sources say that 7.8 to 8.4 is an acceptable range and that stability is more important than the actual number. I know most reef aquarists strive for 8.2 - 8.4. However, many of them drip Kalk and/or have additional equipment to keep pH high. Lastly, most of the pH test kits are junk (including salifert) and most of the people giving advice don't really know what their own pH is. Just my 2 cents.