Alkalinity & pH low

TracyLynn

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This is my on going battle- Low pH & alkalinity with high phosphates. 75 gallon tank.

Today’s water tests:
Salinity - 30
Gravity - 1.022
Ammonia - 0
pH - 7.83
Nitrite - 0
Nitrate - 5.0
Magnesium- 1350
Calcium - 400
Alkalinity- 7.4
Phosphate - 0.236 ppm. 77 ppb

In the sump, I have Chaeto in first section, a cylinder of Co2 media connected to the protein skimmer & a reactor with a 1/2 cup of carbon & GFO.
I just added some salt water to the ATO today since it’s a little low too, I think I’m having a lot of evaporation going on now.
I did a 20 gal water change last weekend, I use Fritz RPM salt.
Thanks so much for helping me work on getting these levels were they should be & hopefully keeping them there.
 
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TracyLynn

TracyLynn

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I don’t really dose regularly. I have used baked baking soda, I also have kalk on hand. I’m just not really confident that I’m doing it right and also don’t care for the residue the kalk leaves on my ATO equipment, as I don’t know what the long term affects it’ll have on it.
Thanks
 

Reefer5640

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Have you tried soda ash? I use sodium bicarbonate to make large adjustments but soda ash to maintain my alk level. It keeps pH a bit higher. I was going to suggest Kalk but if you don’t like to put it in your ATO res then the only other option would either to employ a Kalk reactor or keep it in a separate container and dose the lime water. Kalk would have the biggest effect on your pH of all the options as far as dosing goes.

Your phosphate though is what I would say is the center of your problem. It’s fuel for photosynthesis which releases carbon dioxide which drops your pH. Phosphate become harder to battle in lower pH, it becomes a cycle... What water do you use to top off your tank? Are you using tap, RO, RODI? Also have you considered running a media reactor with some sort of phosphate absorber like GFO or phosguard?
 

GWHouston

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How old is the tank? I had the same problems and now I can reasonably say that my tank had not finished its complete cycle. Start growing your pod population and dose some phyto plankton to help them grow They will help complete your cycle plus feed your fish, especially if you have or will have a mandarin
 

Tomoko Schum

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Your phosphate though is what I would say is the center of your problem. It’s fuel for photosynthesis which releases carbon dioxide which drops your pH.
The part about photosynthesis releasing Co2 and depressing pH is only true for dark hours. Photosynthesis generates O2 when Chaetomorpha is lit and increases pH by taking up CO2.
If you would like to raise your pH and alkalinity, I would start with supplementing with baking soda more regularly. Spiking ATO with kalkwasser works, too. The white substance in your ATO reservoir is just calcium carbonate. It’s harmless. If you don’t like the looks of precipitated CaCO3, you can periodically clean your reservoir. If baking soda does not bring up pH enough, you might consider soda ash. Heating baking soda in the oven to get rid of moisture and contained carbon dioxide is another method. The resulting fluffy white substance will raise pH better than regular baking soda.
 
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TracyLynn

TracyLynn

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What water do you use to top off your tank? Are you using tap, RO, RODI? Also have you considered running a media reactor with some sort of phosphate absorber like GFO or phosguard?
I use RODI water, I have a BRS 6 filter system.
I am running a reactor with a 1 to 1 mix of carbon & GFO.
I also when needed use PhosphateRX drops.


How old is the tank?
The tank is about 3.5 years now. I do have a Mandarin & I feel like I have plenty of pods, as he is a little fatty ;)

@Tomoko Schum I use Fritz RPMsalt mix these are their parameters for this mix:

Parameters:
Salinity: 35 ppt (1.0264 sg)
Calcium: 400-450 ppm
Magnesium: 1300-1400 ppm
Alkalinity: 8.0-9.0 dKH
Strontium: 9 ppm
Potassium: 400 ppm
If you don’t mind we’ll continue this conversation in a bit when I see you. ;Happy
 

Brew12

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I agree that Kalk is a good way to go. If you don't want it in your ATO, which I get, you can set up a drip addition from an elevated container. I think this is better than an ATO anyway since the addition is near continuous and consistent if set up correctly.
 

Monkeynaut

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@TracyLynn do you mix your salt to 35ppt for water changes? I wonder why your tank salinity is 30ppt?
The 30ppt in your tank is possibly the reason you have had trouble With hard corals in the past.

I have run my mixed reef at a pH of 7.8 to 8.0 for a while now with a DkH of around 7 to 8 (So it is probably fine to leave it where it is in your tank if you don’t want to worry with it).

Do you have any Stoney corals in your tank that use alkalinity? Is the alkalinity lowering daily?
 

Reefer5640

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The part about photosynthesis releasing Co2 and depressing pH is only true for dark hours. Photosynthesis generates O2 when Chaetomorpha is lit and increases pH by taking up CO2.
If you would like to raise your pH and alkalinity, I would start with supplementing with baking soda more regularly. Spiking ATO with kalkwasser works, too. The white substance in your ATO reservoir is just calcium carbonate. It’s harmless. If you don’t like the looks of precipitated CaCO3, you can periodically clean your reservoir. If baking soda does not bring up pH enough, you might consider soda ash. Heating baking soda in the oven to get rid of moisture and contained carbon dioxide is another method. The resulting fluffy white substance will raise pH better than regular baking soda.
Good catch. The rest of that sentence should have said ‘after hours’ is what I was driving towards. I was also meaning to mention running a fuge with opposing light cycle if you don’t already have one. Helps more with swings but could be an improvement if you aren’t running one. Not sure what happened to the rest of my post...
 
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TracyLynn

TracyLynn

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@Monkeynaut I do mix my water to 35 when I mix for water change. I was talking to @Tomoko Schum yesterday & all I can think of is it seems I have a lot of evaporation going on lately, seems like we’re refilling the ATO bucket more than usually. I don’t see any evidence of a leak (thank goodness). Unless I read my refractometer wrong, IDK. I do check it with the calibration liquid before I use it.
However, I mixed up & added some salt yesterday & again this morning. The check I ran about 5:30pm today shows the salinity is at 32 / 1.025. I wanted to get the salinity back up before adding either baked baking soda or kalk if bringing the salinity up doesn’t bring those 2 up as well (it’s in the salt mix).
Sorry your last question, asked about Stoney coral - no I only have softies.
I’ll work on getting the salt up & see if that takes care of my issues.
Thanks so much everyone!
 

Tomoko Schum

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Your refractometer should hold the value for months once you calibrate it. Although it's good to verify the value every once in a while, I'd rather not do extra work if I don't have to. I am rather lazy, lol.

As I said earlier, bringing up the salinity should raise your alkalinity some. Therefore, pH should go up some as well. Hope everything will be fine shortly.
 

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