Constant ph drop????

jfenton954 · Mar 1, 2012

I have a 75g reef tank with 170 lbs of live rock, 90 lbs of live sand, 20 lbs of crushed coral in a eshopps 100 sump. I run a algae scrubber with a 10x10 screen for filtration an a coral life 36 watts uv sterilizer an do a 10% water chane a week. I keep having a ph drop, it stays around 7.80 to 7.90. I use kent marine ph super buffer to raise ph but it doesn't stay will drop by the next morning. The water the I use out of my RO/DI is low about 5.60. Should I add the buffer to the auto top off water or get a doser.

Steven R · Mar 1, 2012

What is your KH your KH directly mirrors your ph In stability the more solid your kh the more stable your PH. I f your alk is not right neither will your ph be in check.

jfenton954 · Mar 2, 2012

My KH is 9

VegasRick · Mar 2, 2012

co2 is probably the issue, quite a few threads on the subject here.

jfenton954 · Mar 2, 2012

Having trouble finding the co2 thread....... Did you know where I can find it?

deadmeat · Mar 2, 2012

Yes add the Buffer to your top off water. Also you may like to stop spending a fortune on Kent buffer and use Arm&Hammer Baking soda. <-- same result cheaper experience... I do not understand how dry goods manufacturers still make money selling something I get at the grocery store. Anyway JMO...

Cheers,
Tom

jfenton954 · Mar 2, 2012

Nice..... Thanks for the tip!!! I'll give a shot.

mallorieGgator · Mar 2, 2012

If you use the baking soda, make sure to bake it at 300 degrees for an hour before use to drive off excess water and CO2.

VegasRick · Mar 3, 2012

search doesn't seem to work well right now. You can use google though just use co2 ph site:reef2reef.com
CO2 is usually the cause of low ph in a reef that has alk in the proper range. Adding kw to your top off helps in 2 ways, one the ph of kw being around 11 in fully saturated kw drives the ph up. Two kw combines with co2 in the water to form carbonate.

https://www.reef2reef.com/forums/reef-chemistry-forum/72355-low-ph.html
https://www.reef2reef.com/forums/do-yourself-diy/57609-easy-way-increase-your-tanks-ph.html
https://www.reef2reef.com/forums/reef-aquarium-discussion/62535-ph-keeps-dropping.html
https://www.reef2reef.com/forums/re...49-raising-ph-without-raising-alkalinity.html

Troylee · Mar 3, 2012

Nice signature Rick haha..:tongue:

lpslover · Mar 3, 2012

Frustrating! You might double check your magnesium. Low magnesium can lead to low pH. Also try using a carbonate only buffer rather than a bicarbonate (baking soda) or bicarbonate/carbonate blended buffer. Bicarbonates don't buffer to a high enough pH, and the carbonate gets depleted as the tank's metabolism will convert it to bicarbonate. (Bulk Reef Supply has cheap soda ash for this purpose.) You can also reverse this conversion, and increase the pH by dosing hydroxides (Kalk if you need the calcium, or Balance by AquaVitro if you don't.) Good luck!

mcarroll · Mar 16, 2012

jfenton954 said:
I have a 75g reef tank with 170 lbs of live rock, 90 lbs of live sand, 20 lbs of crushed coral in a eshopps 100 sump. I run a algae scrubber with a 10x10 screen for filtration an a coral life 36 watts uv sterilizer an do a 10% water chane a week. I keep having a ph drop, it stays around 7.80 to 7.90. I use kent marine ph super buffer to raise ph but it doesn't stay will drop by the next morning. The water the I use out of my RO/DI is low about 5.60. Should I add the buffer to the auto top off water or get a doser.

First, it's a bad idea to worry too much about pH. Many variables contribute to the number on your tester and you really don't want to get into chemically manipulating one or two of them if there's no really good reason to do so. If your tank looks healthy and all the other numbers are in order, my instinct would be to ignore the low pH as an aberration.

With that in mind, definitely double check your Ca and Mg concentrations and make corrections as needed. Assuming they are already correct, another possible solution which may be may be more direct than some of the other chemistry-oriented solutions already presented is to draw fresh air (vs house air which is CO2-saturated) into your tank via the protein skimmers air line. Run it out through a door or window. This will prevent as much CO2 from dissolving into your tank as appears to be happening now. Also, while I would not consider this first, there are also CO2 scrubbers you can connect to your system which will accomplish much the same thing. They are expensive compared to running an air line outside though.

Because it's cheap and easy to do and would be good for your tank anyway (multiple posts on chemistry issues), I would also consider doubling your water change rate (do two changes in the same time period, or one change that's twice as big) and see if that has an impact.

-Matt