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Consistant pH of 7.5, can't raise it higher


Admonition

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I recently moved over a two year old tank (nuvo16) into a larger tank (fusion 30L). The tank has been running great for the past month; however, the pH has been wicked low since the move. No matter what I do the pH seems to stay steady at low of 7.5 and a high of 7.7. These readings are coming from a Salifert Test kit, API test kit, and my Apex probes, so I know they're accurate readings. Naturally I'd rather have the pH higher than 7.5, so I've tried to increase the pH through water changes. I've done five gallon water changes, introducting new water with a pH of 8.2 (which is normally what I would add to the old tank). But even with the 25% water change with a pH of 8.2, the tank still ends up with a pH reading of 7.5/7.6 shortly thereafter.

 

I know static pH is a good thing, but I'm certain a pH of 7.5 isn't the best for my corals and fish. Does anyone have any suggestions on what could possibly be going on to make my tank stay at this pH no matter what? And does anyone have any better suggestions as to how to safely raise the pH?

 

My tank details are as such (more info can be found via my link in signature):

 

Temperature: 78.5 F

Ammonia: 0

Nitrate: 0

dKH: 8.0 (plan to raise it to 9 with BRS two part later tonight)

Salinity: 1.025

Calcium: 425

Magnesium: 1340

Phosphate: 0.05

 

*About 20 gallons of toal water volume

*I do 25% water change every two weeks

*I use Tropic Marine Pro Reef Salt mixed with RO/DI water from my Spectrapure system

*I run Chemi-pure Elite, Purigen, and inTank Filter Floss in rear chambers

*I have about 15lbs of two year old LR covered in coralline algea and about 13lbs of BRS Reef Saver Dry Rock

*I use RO/DI water to top off via my Tunze ATO

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First of all.....never, never, never chase #'s. You're most likely to do more harm than good in doing so. If your livestock is healthy I would lave it alone.

 

How's your surface agitation? Point a power head up toward the surface, your pH will likely rise with better gas exchange.

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My well water is a bit acidic, and it's probably because of dissolved CO2. Do you run a skimmer? I wonder if more oxygen would help you. I'm sorry that I don't have anything better (or magical) to share.

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glennr1978: I know, I'm horrible lol, but I can't help looking at my 7.5 pH and thinking my corals might do better in 8.2ish pH. As far as my surface agitation its great. I have both returns pointing upwards, breaking up the top water across the entire length of the tank.

 

Steve973: I do not run a skimmer at all, my research led me to believe that it would do more harm than good on a small tank like mine :)

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Steve973: I do not run a skimmer at all, my research led me to believe that it would do more harm than good on a small tank like mine :)

There's no way it'll do any harm. The worst that can happen is that you get micro-bubbles for some amount of time until you get it adjusted properly and/or until it breaks in. Getting organic compounds out of your tank before they begin to break down is one of the best things that you can do for the organisms you're keeping.

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Maybe I'll look into one eventually :)

 

So, any ideas on why I can't seem to get my pH to rise, even with higher pH water changes? Any other suggestions on raising pH safely?

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Where do you keep the tank? Mine is in the basement and I had a terrible time with ph until I opened a window and got some fresh air circulating. Do you have newer windows? Maybe you are just too sealed up? If fresh air helps but it's not ideal, maybe a co2 scrubber would work for you. You can get the supplies at BRS.

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My tank is in the living room of my apartment, and we usually keep the windows closed. I'm

Not sure I understand how closed windows would effect pH, can you explain? I never had a problem at my last place.

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Sometimes if your place is nice and sealed up co2 will build up in the room. When the gas exchange in the tank takes place the lower available oxygen will in turn drop the ph. I'm no scientist myself so that's the only way I can try and explain it.

 

There are some folks that go as far as running the air intake of their skimmers outside to draw in more fresh air.

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My tank is in the living room of my apartment, and we usually keep the windows closed. I'm

Not sure I understand how closed windows would effect pH, can you explain? I never had a problem at my last place.

CO2 converts to carbonic acid in saltwater and lowers the pH. Carbon dioxide build up inside of newer homes/apartments is a real problem. Adding additional surface agitation or a skimmer will not help as you are just mixing more air with elevated CO2 into the tank. Open a window or figure out how to get air into your tank from the outside.

 

Don't chase pH.. but you do need to do something when it's only 7.5 at the end of the day. 7.6-7.8 is about the lowest swing that I'm comfortable with. I'm at about 7.95-8.15 on my larger tank.

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glennr1978: I know, I'm horrible lol, but I can't help looking at my 7.5 pH and thinking my corals might do better in 8.2ish pH. As far as my surface agitation its great. I have both returns pointing upwards, breaking up the top water across the entire length of the tank.

 

Steve973: I do not run a skimmer at all, my research led me to believe that it would do more harm than good on a small tank like mine :)

I'd point one of the two returns down into the tank. You'll get better in-tank water turn over. Otherwise you are just turning over the top part of your water column.

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CO2 converts to carbonic acid in saltwater and lowers the pH. Carbon dioxide build up inside of newer homes/apartments is a real problem. Adding additional surface agitation or a skimmer will not help as you are just mixing more air with elevated CO2 into the tank. Open a window or figure out how to get air into your tank from the outside. Don't chase pH.. but you do need to do something when it's only 7.5 at the end of the day. 7.6-7.8 is about the lowest swing that I'm comfortable with. I'm at about 7.95-8.15 on my larger tank.

 

 

Yep there's the scientist I was looking for ;) Thanks for the better explanation.

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Wow I had no idea, thank you guys for the help. I currently live in an older condo (built in the mid eighties) in Florida. We never have the windows open because of the heat.

 

Given what you've all recommended, do you believe if I ran an airstone in the tank that could raise the pH? I was under the impression that an airstone would lower the pH, because I actually used to use them to lower the pH of my newly mixed saltwater (haven't done that in awhile).

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Fishgirl2393

It will only help if you run it outside. My tank had low pH like that, I ran the air pump that runs my skimmer outside, and the problem was solved. My pH now runs about 8.2 (lowest is 8.0).

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I'm sorry, I don't understand what you mean by outside. I don't have a skimmer. When I say airstone I simply mean dropping in a basic $2 airstone into the tank (rear chamber of my AIO), and attaching it to a Tetra Whisper air pump via airline tubing, and I'll have the pump sitting under my tank (in the stand).

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You need a source of fresh air that has less CO2 in it. If you have a skimmer you can run the air intake to the outside so it pulls in fresh air. I don't know if there's an air pump that would allow you to do that.

 

I had a similar issue to you and when I ran my skimmer line to the outside it brought the pH up nicely.

 

If you don't want a skimmer, you could try what the other posters have said and increase gas exchange by increasing surface agitation. Your air stone will also do this but may not make any difference. Worth a try!

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Fishgirl2393

My air pump is outside (it is an air pump driven skimmer) so you COULD do the same thing with an airstone. Just get a LOT of tubing, run it through the window/door/whatever and plug it in outside. It works. The air inside is saturated with CO2 which is why your pH is so low. Therefore, the air pump would be simply pumping more CO2 into the tank, therefore lowering the pH more. My pH was as low as yours as well, but now, it is not.

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Ah, gotcha. That would probally explain why the pH of my newly mixed saltwater (for water changes) is easily brought down to a reasonable level when I throw in my airstone. I just didn't know the science of why that was happening.

 

I guess I'll try mixing my saltwater outside and see if that helps. I'm curious though, I have put new water (with a pH of 8.2) in the tank, only to have it drop back to 7.3-7.5 in hours. So even if I start mixing my water outside before adding it from now on, that won't solve the problem right?

 

Unless my science is off, I'll need some way of consistently adding air saturated in oxygen into the tank right?

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Fishgirl2393

Correct. You really will only have luck by adding air from outside to the tank. If possible, running an air pump outside will likely solve your problems.

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Well that sucks. There's no way I can run outside air via a pump to the tank. So it seems the only option would be opening windows and seeing if that helps, or trying a skimmer.

 

Random question. I did some research and I came across something about chemi-pure elite. It said that chemi-pure elite will maintain your tank's pH, and that you should have your pH where you want it before adding the product. Does anyone know if there's any truth to this? Could this simply be the result of me adding chemi-pure elite when my pH was around 7.5?

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Not personally but as soon as my new tank gets set up I will be using one. Those who I have spoken with that have used them report a rise and stabilization of ph.

 

A skimmer isn't going to really help you out, it's still drawing the air from in the room. I have run a skimmer since day 1 and I still have to have a window open almost always.

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Add 1 tsp kalkwasser to 1 gallon of your top off water. When your pH goes to 8.2-8.4, then buffer it. Don't add anymore external calcium as the kalkwasser will raise your pH and provide the tank with calcium. You will have to do this on a regular basis (once every 2-3 weeks for me) depending on when your pH slowly becomes more acidic again.

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