Marine Salt lower pH levels?

The friendliest place on the web for anyone with an interest in aquariums or fish keeping!
If you have answers, please help by responding to the unanswered posts.

fearkitten

Aquarium Advice Newbie
Joined
Apr 3, 2011
Messages
5
I'm running a 30 Gallon reef tank (been up and running for about 3.5 months now) and keep encountering pH levels that are lower than recommended/normal and I fear what long term effects this will have on my fish/corals. All other parameters in my tank have been testing at normal levels but my pH runs relatively at about 7.4 to 7.5 on any given day. Everything in my tank looks healthy and happy at least, but I obviously want to do my best to provide the best quality water chemistry I can for my stock in order for it to thrive well in the long run.

After performing hours of online research I tested a couple theories and still have no real answers.

First I took into account that gas exchange may have a negative effect on maintaining my pH levels so I measured the pH of my tank water (7.5 as usual) and removed a glass full and aerated it with an airstone for an hour, then remeasured the pH of the water in the glass and there was no change. This was not really all that surprising to me though as I have adequate water movement throughout the tank (377 GPH) and one of my power-heads is specifically positioned upward to break the water tension and remove the chance of poor gas exchange in my water (also no lid for better oxygen flow).

Second I read in multiple places that using liquid Amquel can lower pH quite drastically in certain water conditions. I usually was using it to treat my tap water before water changes so I thought perhaps this was the culprit. I measured the pH of my tap water right out of the sink and it read at 8.7 pH.
Then after adding proper amounts of marine salt and Amquel to a 5 gallon bucket of tap water, I remeasured and it dropped down to 7.5 as expected. So for a moment I was convinced it was the Amquel. I dumped that bucket of water and made a new batch, this time I treated the water with Prime first - which, when added on its own into the freshwater had no effect on my tap's pH levels as they still read at about 8.7 but as soon as I mixed in my marine salt it dropped back down to 7.5!

Is it possible that the marine salt is having this effect? And if so why/how and what can be done about it? Or am I just an incredibly dumb newbie who is missing something really obvious? Any clues as to why this is happening would be very much appreciated! And apologies in advanced if this is a dumb question...
 
It's very possible you have a high co2 level in the air in your house.
Your airstone experiment wasn't done exactly right. What you want to do is take that sample outside and pump outside, fresh air into it. Then test the pH. If it goes up to around 8, you have more than average amounts of co2 in the air in your house.

You can also read this article for some other tips on raising your pH.
Low pH: Causes and Cures by Randy Holmes-Farley - Reefkeeping.com
 
Thanks for the response. What you recommended was mentioned to me on another board so I will be sure to aerate some freshly mixed salt water out of doors as soon as I get a chance and get back to you on that - if there are still no changes I will try a different pH test to be sure (currently using an Oakton Eco digital pH meter that is supposed to measure within a ±0.1 accuracy range so I would be really disappointed if that were the cause of the low pH results) but to be honest I would be really surprised to find if we have much excess CO2 in our home as we leave our doors and windows wide open through a majority of the day to freshen up our house and we also have many house plants which I would assume would help with reducing any CO2 that there is...
 
Currently I am using an Oakton Eco digital pH meter that is supposed to measure within a ±0.1 accuracy range and Crystal Sea Marine salt. I thought perhaps the salt was the problem so I have a large bucket of Oceanic coming in the mail next week.
 
I was just wondering if the ph meter was not measuring the salt water accurately. or it could be the tap water if you have access to some r/o water i would try that too. good luck
 
Thanks that is a good theory actually - the meter I am using is actually designed for gardening/plant use and therefore probably designed for freshwater. So, perhaps it can't properly read it once the salt has been added. I will have to get a new tester tomorrow from my LFS when stores are open again and try that theory out. :)
 
The meter should work fine in saltwater. Have you calibrated it with proper solutions yet? I start by calibrating mine to 7ph, then calibrate the high end with 10ph.

One last thing, if you are going to the expense of having a PH meter, you should really invest in a simple RO water maker and get away from tap water. Tap water has all sorts of solids dissolved in it, depending on the region you are from. These solids can react to the minerals in your salt mix and do some strange things sometimes. It also changes from month to month. Think about all the trouble you have taken to eliminate any metal piping or objects from your salt tank, only to fill it with water that ran thru copper and lead pipes to get to your faucet.
 
It was indeed the pH meter that was throwing me off. I purchased a droplet test kit today and my water is now reading at a healthier 8.1 instead of 7.5. So, lesson learned here - gardening pH or any pH meters not intended specifically for saltwater use will not produce accurate results for saltwater pH. Thanks again for your help everyone!

And on the topic of RO water, this is definitely something I am going to start purchasing rather than using crappy tap! Thanks for your input! ^_^
 
Back
Top Bottom