Unable to maintain pH

[EMS503]

My tank is a 75 gal. reef with a 20 gal sump & 15 gal. refugium. This tank has been running for 3 years with its ups & downs.
It has a 4" live sand bed & approx. 100 lb of LR in the 3 tanks.
Tonight I checked my levels and found my pH at 7.8, this will vary from 7.8 - 8.1 at any given point during the day. I just did a 10 gal. water change and added 1 bag of live sand last night. My make up water is made with a Kent max 60 HIS R/O unit. I am on well water the house water is a constant 7.0 & the R/O unit is 6.6. I have tried to raise my pH with Seachem pH 8.3 Marine Buffer which does not really help and drives my Alk. through the roof. My top off water is R/O water with aragaMight mix in to maintain my calcium. I am stumped as to how I can raise my pH up into the 8's without throwing something else off. All the corals, Fish & Caulpera are thriving. Since I just upgraded my lights from VHO to 2 - 175 watt/MH with 2 65 watt PC's
even the coraline algae is making a come back. Since my tank seems to be accepting this pH level should I just leave it or try something else. My other levels are temp 82, salinity 1.026, Nitrite, Nitrate, ammonia & Phosphates are 0, Calcium 490, Alk 11.7.
Any thoughts or suggestion would be appreciated Thanks.

[bongobrian]

There are a lot of variables that come into play with PH, and several ways that you can adjust it. First of all, what kind of test kit are you using and what time during the day are you testing? remember that you typically get a drop in ph after the lights go out until when the lights come back on, and it is normal to have fluctuations in ph throughout the day. Your ph is a tiny bit low, but if nothing is showing stress, I really wouldn't worry about it. I am surprised the seachem buffer hasn't helped, and I find it odd that it would alter your alkalinity... it shouldn't be doing that and suggests your system may have an ionic imbalance. Are you sure you aren't adding the ph buffer along with something else? a lot of times if you use two additives within a short amount of time or even the same day, you could be causing them to pricipitate out of solution. So if you're using a carbonate hardness buffer like seachem reefbuilder along with the ph buffer, you might just be making expensive gravel instead of powder actually being dissolved. You really should be able to alter the ph without it effecting anything else. What else are you adding to the tank besides the buffer? what type of lighting cycle are you using on your refugium? using either a reverse cycle or 24/7 lighting on the fuge will help keep the ph up. Dripping kalk would probably also help bring the ph up. Here's another thought: maybe you have too much carbon dioxide being dissolved from the air. Do you have a lot of surface agitation or bubbles going into the system? hth.

[bongobrian]

sorry I meant to say you may have an excess of carbon dioxide from the lack of air.... perhaps there isn't enough surface agitation for good gas exchange.

[bongobrian]

ya know what I just checked out seachem's website and they do in fact say that the reef buffer does raise alkalinity. I use the same products and never knew that! I always thought they marketed those products to adjust specific levels independent of one another.. but maybe that just goes for the reef builder and reef advantage.

[kevinpo]

You can add Arm & Hammer washing soda (sodium carbonate). 1 box will last you years. Be very careful to add only a very small amout at first as it is very powerful. On your tank, I would start with 1/2 teaspoon dissolved in some makeup water. Then check the PH 4-6 hours later. As stated above check the PH at the same time each day.

HTH,
Kevin

PS: Washing soda can be found in most grocery stores. If you can't find it let me know and I'll send you some.

[EMS503]

Kevin are you talking about baking soda (Sodium Bicarbonate)?

My test kit for pH is Aquarium systems Fast Test

For surface agitation I have a .5" pvc spray bar that shoots across the top of the tank (return from my sump) along with two Hagan 402 PH mounted just below the surface of the water. pH was tested in the eve. hours after the lights came on. Refug. lighting is reverse cycle.

Thanks all for the quick replys.
John

[kevinpo]

EMS503,
No I'm talking about Washing Soda which is sodium carbonate. It has a very high PH (14 I think. My test kit doesn't go that high).
It is available in many grocery stores.

It can be used in combination with baking soda as an inexpensive buffer at a ratio of 6 parts baking soda to 1 part washing soda.

Here is a link to some good information and pictures of the product:
http://www.hawkfish.org/infoctr/homebuffer.htm

Regards,
Kevin

[EMS503]

Found the wash soda it worked great. I forgot to ask will this raise my Alk. also.

[oscar c]

if the corals & fish are not stressing.let it be that ph swing is normal in some systems.

[kevinpo]

It will, but likely it will raise your PH too high before your alkalinity gets to the level you desire. Mix it with baking soda per the above ratio and it will raise your alkalinity without driving the PH through the roof.

HTH,
Kevin