Why Am I Having pH Problems?

[Rcpilot]

I do weekly water changes. Every week, between 5--8 gallons. Tank is 30g. I'm using RO/DI water from a 6-stage unit thats brand new.

I have 40lbs of crushed n smashed n ground up coral under my DSB. It's easily 4" deep. I have another 1.5" of fine white reef sand on top of that DSB.

I have 4-5" DSB in my refugium using live sand.

I have a great skimmer.

I have 61lbs of live rock in my tank and it's growing coraline very nicely.

I have more than enough water circulation.

Tank runs 78-80F. Salinity is 1.023--1.025 (used to keep it lower, but in the past months have slowly let it climd up to 1.025)

All my other parameters are good. But, I'm getting weekly readings of 7.8 pH. I'm testing my water in the middle of the day, on my lunch break.

Any ideas? Is it normal? Something I'll just have to live with?

Thanks

 

[reeffreak]

I'm not sure what is causing the lower than expected PH.Usually an aragonite sand buffers the system.I know crush coral tend to lose that ability as it gets older.You already have a refugium on opposite lighting of your display,right?IMO,RO water is usually low on the PH side.Either start dosing the freshwater or your system.I like "Proper PH 8.2" and "Seachem Buffer 8.3" since both products won't overshoot the PH.Test alkalinity because those products can raise alk too.

 

[fishbait]

some salt mixes such as instant ocean have a low ph. the only way to raise up to normal is with a buffer like reeffreak was talking about.

 

[yote]

Im thinking along the same lines as Fish.
Could be your salt mix.What brand are you using?

 

[Rcpilot]

I just bought the mega 160g bucket of Instant Ocean from the 2 docs. I've only used about 20 gallons of it so far. So, I'll be using that for some time. Unless I buy another bucket of a different brand and mix the two.

I went out this afternoon and bought some Seachem reef buffer. I have been testing more frequently and registed a consistant 7.8 with 5 different tests at different times of the daylight hours. This was in the last 24hr period. So, I decided to dose it with the reef buffer.

The directions call for 1 level teaspoon per 40g to raise pH .1 points. My tank is 30g, so I did go ahead and use the full teaspoon since my tank was only 7.8. I mixed it with about 2 cups of RO water and used a drip to siphon it into the tank over about 3hrs.

I tested tonight and I'm getting over 8.2, but not quite 8.6 Hard to read exactly with these color charts.

So, now that it's at the right pH, will it remain stable until the next water change? Or will I have to monitor it daily and see if the tank uses it and needs dosed again?

Is there a way to make it buffer or maintain pH naturally? More sand? Less food?

Edit:
I do not run a reverse light cycle. I need to build some sort of panels to stop the light from my refugium from bleeding into the tank. The way it sits now, when my refugium lights are on, the tank is pretty well lit up. The refugium light sits on top of the HOB refugium and the light bleeds out and down on top of the tank. I have a black back on my refugium. It's not bleeding in the way. The light is coming from the top. I know I need to build something to stop that light, but just too lazy.

 

[Bifferwine]

I bet it's your salt. A lot of people have had problems keeping the pH up with Instant Ocean.

 

[yote]

To be safe,I'd test it every day for a while to see how fast it drops PH.

I think somebody has been mixing Instant Ocean and Oceanic at half and half.

 

[Rcpilot]

I might buy some of that Oceanic salt and mix it.

Wasn't somebody using Reef Crystals? Or mixing them with Instant Ocean?

 

[SSalty]

I could be wrong, but isn't a 5-8 gallon weekly water change a little big for a 30gallon? Could this possibly cause low PH? I do no more than a 5 gallon water change on my 55 gallon every week use IO Reef Crystals and have no problems with PH.

Not sure, just throwing this out.

 

[reeffreak]

I think I've use almost every salt mix on the the market.They always been spot on when it came to pH.

What is the pH of a freshly made up saltwater?

 

[Rcpilot]

I haven't checked the pH of my RO water. Never thought of that. I'll do that this weekend. I also have not checked the pH of freshly mixed saltwater either. I'll do that as well.

I feel silly now for not testing it. Why wouldn't you? I really want to know what I'm putting IN the tank now.

 

[Rcpilot]

Down to about 8.0 this evening at 8pm. Lights just went off, so I'll test it tomorrow morning right before they come back on.

Tested my RO water. pH is 7.8

Tested fresh salt mix with RO water. pH 8.2

Now I'm getting a little worried. I had low pH and bumped it all the way up to somewhere between 8.2 -- 8.6. It held for about 24hrs and is dropping now. I haven't established a pattern yet. I just know it's dropping. I'm going to test it in a "worse case scenario" tomorrow morning before the lights come on. Then I want to monitor it mid day and evening, after the lights have been on for some time.

I need to establish a pattern and fix it or stabilize it so that I'm not experiencing drastic pH swings on a daily basis.

I tested everything today.

ammonia 0
nitrite 0
nitrate 0
phosphate 0
calcium 480
dKH 9.3
alkalinity 3.31
Iodide .03ppm

That's all the test kits I got. Everything seams normal except the pH.
:frustrat:

 

[reeffreak]

Remember if your dosing,wait 24 hours before testing.Also 8.0 is pretty good.

You do have your lighting for the fuge on opposite cycle than the display,right?
You do have aragonite sand,right?

 

[Rcpilot]

My refugium is not on opposite cycle. I know it should be.

Did not know I had to wait 24hrs to test after dosing. Thanks.

 

[reeffreak]

Macro and micro algae produce oxygen as a by product through photosynthesis.Lower O2 and higher Co2 causes pH to drop.Thats why pH is lower when the lights are out usually.I believe putting your fuge on opposite lighting will help in your situation.

 

[Rcpilot]

From post #5:

I do not run a reverse light cycle. I need to build some sort of panels to stop the light from my refugium from bleeding into the tank. The way it sits now, when my refugium lights are on, the tank is pretty well lit up. The refugium light sits on top of the HOB refugium and the light bleeds out and down on top of the tank. I have a black back on my refugium. It's not bleeding in the way. The light is coming from the top. I know I need to build something to stop that light, but just too lazy.

I'm not convinced this is 100% my problem. I think I have plenty of oxygen in the tank, but can't say for sure because I don't have a way to test it. My skimmer has got to be putting some oxygen into the water. I've got 2 powerheads that do nothing but boil the surface of the water to help with gas exchange. Those should be putting oxygen into the water. And my refugium return line creates lots of turbulance where it dumps the water back into the tank.

Guess I'll buy an oxygen test kit.

 

[Bifferwine]

It really has nothing to do with the oxygen content of the water. It has to do with the photosynthesis of the plants. When plants are photosynthesizing (in the light), they take in CO2 (carbon dioxide) and expel O2 (oxygen). When they are not photosynthesizing (in the dark), they are not taking in the carbon dioxide. This turns into carbonic acid, which lowers the pH of your tank (because it's an acid). It doesn't have anything to do with powerheads or water movement.

That's why it's good to run the fuge lights opposite the main tank. During the day time, the photosynthetic organisms in your tank (micro algae, corals, etc) are converting the CO2. When the lights go out, there is nothing in the main tank doing that. So if you run the fuge on the opposite schedule, the macro algae will do it during the night.

 

[Piggy]

So you should have your main tank lights on during the day a fuge light on at night? If so how can you prevent the light from HOB fuge from lighting up your tank at night?

 

[reeffreak]

It really has nothing to do with the oxygen content of the water. It has to do with the photosynthesis of the plants. When plants are photosynthesizing (in the light), they take in CO2 (carbon dioxide) and expel O2 (oxygen). When they are not photosynthesizing (in the dark), they are not taking in the carbon dioxide. This turns into carbonic acid, which lowers the pH of your tank (because it's an acid). It doesn't have anything to do with powerheads or water movement.

That's why it's good to run the fuge lights opposite the main tank. During the day time, the photosynthetic organisms in your tank (micro algae, corals, etc) are converting the CO2. When the lights go out, there is nothing in the main tank doing that. So if you run the fuge on the opposite schedule, the macro algae will do it during the night.

Hellooooooo!Thats what I said!
You do explain it much better than me.

Piggy,I don't know how you can block the light.Perhaps some black plastic to shield the light.I read many people running HOB fuges 24/7,but I don't prefer that method.

 

[Bifferwine]

I run mine 24/7 because it's not on a timer yet, and I always forget to turn it on and off.

If it lights up the tank a little bit, that's okay. Remember in "the wild" moonlight usually keeps the ocean pretty bright on some nights.