Im not sure about what sand you have, but it definatley looks like it has some sort of water altering properties.

I use this pool filter sand. Uniform in size and I have not had any problems with it in 3 years. Its also dirt cheap.

 

It's odd. From everything I've read, on this site and elsewhere, HTH sand is great for freshwater. But yeah, it's definitely raising the pH.

I can't chance it again. I'm going to get some actual aquarium sand even if it means paying more.

 

Did you let sit your tap water for over 24h prior testing ? It could be that your tap water contains co2.

 

That's very weird. I have well over 200lbs of that same exact sand and I'm not seeing any PH buffering with it. My tap ph is between 7.4 - 7.6, and that's what my degassed tank water sits at. If it was causing my PH to rise, I'd use way more CO2 than I actually am. I've been running the same 10lbs CO2 tank since around Memorial Day so if the controller was up against constantly rising PH I would have exhausted that tank months ago.

I'd ignore the "compatible with salt systems" tag on there because all pool filter sand is compatible with salt water pools/spas. The reason it's compatible with salt water pools/spas is because it's inert and doesn't have any buffering capabilities.

What else do you have in your tank? Rocks, decorations, etc.

What I'd do to eliminate variables is take two water samples....one from your tank and one from the tap. Let both sit out 48 hours and then test them both.

If you want to get really crazy, take a third same with tap and toss some sand in the sample...roughly approximating the sand to tank water ratio and let that sit 48 hours as well.

If those three samples all come out relatively close to one another, then it'll at least give you the ability to eliminate a variable.

But pool filter sand is silica which is PH neutral (7.0). Aragonite is the stuff that buffers PH, which can't be used in saltwater pools/spas because of its PH altering properties. Aragonite is great for saltwater aquariums or African Cichlid tanks but not for much else.

 

What else do you have in your tank? Rocks, decorations, etc.

+1 for listing the other objects in the tank, especially rocks. Unless the bag is contaminated it should be pH neutral and inert.

Did you let sit your tap water for over 24h prior testing ? It could be that your tap water contains co2.

He mentioned that his tap water tested neutral. I would think that CO2 would drop the pH not make it more alkaline(higher).

 

I'm quite confused by this. I've done some testing since yesterday, so let me list those results along with the original ones and answer some other questions asked above.

• I have Manten stone in the tank, and a piece of black spider wood that had been soaking for about two months. Other than that, only the sand. I also have mechanical/bio media and carbon.
• The pH of the tank when it inspired me to make this post was 8.15, approximately one day after filling it up for the first time. I didn't rinse the sand.
• After posting yesterday, I changed 90% of the water. The pH went back down to ~7.2, which is the right pH for NYC tapwater (correction from where I said it was "dead neutral").
• Then it started climbing slowly throughout the day and topped off at 7.58 before retreating to 7.45 this morning. Still higher than the spec sheet for my tapwater, but not crazy high.
• I took some tank water with sand, some tank water with Manten stone, and some tap water, and let them sit overnight. Tested them just now and they all varied slightly between 7.25 and 7.31, lower than the main tank. I'll test them again tomorrow.

I have few theories. Maybe there was something in the tank or the sand that spiked the pH when I first filled it and the water change got rid of it? It does seem that it isn't the sand after all, but something is at least somewhat increasing my tank pH.

It's an utter mystery why pH was so high yesterday. I might need to recalibrate my meter (calibration chems are coming tomorrow) but not by that much. I was pretty careful calibrating it. I can't throw out the result as a white elephant, it was definitely high.

I didn't know about degassing a water sample. I'm new to planted tanks. So if I understand that correctly, it means to let all the C02 evaporate to get a true pH reading on the water, and that may be higher, due to less C02?

Suggestions welcome!

 

I'm quite confused by this. I've done some testing since yesterday, so let me list those results along with the original ones and answer some other questions asked above.

• I have Manten stone in the tank, and a piece of black spider wood that had been soaking for about two months. Other than that, only the sand. I also have mechanical/bio media and carbon.
• The pH of the tank when it inspired me to make this post was 8.15, approximately one day after filling it up for the first time. I didn't rinse the sand.
• After posting yesterday, I changed 90% of the water. The pH went back down to ~7.2, which is the right pH for NYC tapwater (correction from where I said it was "dead neutral").
• Then it started climbing slowly throughout the day and topped off at 7.58 before retreating to 7.45 this morning. Still higher than the spec sheet for my tapwater, but not crazy high.
• I took some tank water with sand, some tank water with Manten stone, and some tap water, and let them sit overnight. Tested them just now and they all varied slightly between 7.25 and 7.31, lower than the main tank. I'll test them again tomorrow.

I have few theories. Maybe there was something in the tank or the sand that spiked the pH when I first filled it and the water change got rid of it? It does seem that it isn't the sand after all, but something is at least somewhat increasing my tank pH.

It's an utter mystery why pH was so high yesterday. I might need to recalibrate my meter (calibration chems are coming tomorrow) but not by that much. I was pretty careful calibrating it. I can't throw out the result as a white elephant, it was definitely high.

I didn't know about degassing a water sample. I'm new to planted tanks. So if I understand that correctly, it means to let all the C02 evaporate to get a true pH reading on the water, and that may be higher, due to less C02?

Suggestions welcome!

Degassing just allows the water sample to allow any gases present in the water to dissipate. Some recommend 24 hours, others 48 hours. If I need to test a degassed water sample, I just leave it out for a couple days and set a reminder on my phone for when it's ready to be tested. The only time I've done this is to test my tap water, and my tank water so that I could get baselines for the amount of CO2 I plan on injecting, or if something wonky is going on.

From what I understand Manten stone is Ph neutral. I don't know a whole lot about it, but just recall when I was looking for stone that was one of the ones that didn't mess with the PH.

 

Yeah, everyplace that sells Manten says it's pH-neutral and the tests seem to bear that out. At least I know it's not the driftwood

So explain this.

• Yesterday after filling the tank: pH of 8.12, even though my tapwater is 7.2.
• Today, after changing 90% of the water yesterday: pH rose from 7.2 to 7.6ish and now has dropped back down to 7.39.

I'm tempted to write this episode off and stock the tank.

 

I would test tap and tank water that has set for a day or two. A change of .2 in ph could be several things. I also would like to point out that water quality reports can vary greatly from what comes out of your faucet.

What are you using to measure ph?
What do you mean by stocking the tank?

 

I shouldn't have said stock, I really meant "start cycling the tank". I'm using an American Marine pH probe and an API kit to correlate.

 

One possible explanation is your probe is not accurate.

Another possible explanation is that your stone is not what its supposed to be.

Another possible explanation is that your stone (or something else) had on it a ph altering substance (could be rock dust, or dirt).

Another possible explanation is there was a water main break affecting your tap water.

Another possible explanation is that your city was flushing their pipes (you see this in big cities when they open the fire hydrons). When they do this a lot of gunk gets dissolved into the water supply and changes normal parameters.

Another possible explanation is that your water changed sources. I believe NYC uses reservoirs (surface water) for it's supply and as they change from one to another you could see fluctuations. I know I do where I live in Maryland.

That's all I can think of off the top of my head.

Bottom line is that it can be a lot of things. Chasing down the exact cause of something like this is really a pain in the butt. It's also almost always unnecessary. Keep looking at parameters for a few days. Do another water change, see if it's stable. If it is, then good to go.

 

This is a complete one-off that I'm going to take @minorhero's suggestion on and not worry about. I did two more water changes and recalibrated my pH probe, and now tank water is 7.15, stable. Looks like something alkaline got into the water I originally used. No idea what it was ¯\(ツ)/¯

I'm moving on to cycling and stocking.

 

I'm setting up a new tank and put in HTH pool filter sand from Ace hardware after reading that many hobbyists had used it with success. At least, I thought I did. My pH is now over 8, verified by my monitor and my test kit. My tapwater is dead neutral.

Here's the one I got:

View attachment 1048357 View attachment 1048356

I just noticed that this package is labeled "compatible with salt systems," and also saw the water parameters on the back. So, I'm pretty bummed, but am assuming I got the wrong product. Or I misread the recommendations. I'm not sure. Is this aragonite sand?

Can anyone suggest a sand that won't change my pH? Not looking forward to scooping all this out.

Thanks!

Stupid question, but: did you wash the sand before use?

 

I didn't, but it's silica sand. I wouldn't think there would be alkaline residue. But then, I don't know what happened.

 

If you have any of that sand left, test tap water, rinse the sand in it, then test again.

 

How is the tank doing, Krib?
I'm considering the HTH pfs for my new tank but your experience is concerning.
Any more ph issues?
Did you determine if it was something in the sand causing the problem?

 

How is the tank doing, Krib?
I'm considering the HTH pfs for my new tank but your experience is concerning.
Any more ph issues?
Did you determine if it was something in the sand causing the problem?

Yep, I thought somebody might see this and be concerned! I had an issue with a crashing pH as well, and although I don't have definitive proof, would chalk both of these incidents up to very soft water with no buffering capacity.

I would go for it, provided that you purchase that brand. This was a weird issue to be sure, but there's a body of evidence in the hobby for the viability of this stuff.

As for the tank, it's doing well. Once I buffered my water, the pH stabilized and I quickly got through my cycle. I'll be stocking tomorrow.

 

That's good news on the sand and your tank.
What was your KH value of your water before buffering and what did you increase it to?
Thanks

 

I'm setting up a new tank and put in HTH pool filter sand from Ace hardware after reading that many hobbyists had used it with success. At least, I thought I did. My pH is now over 8, verified by my monitor and my test kit. My tapwater is dead neutral.

Here's the one I got:

View attachment 1048357 View attachment 1048356

I just noticed that this package is labeled "compatible with salt systems," and also saw the water parameters on the back. So, I'm pretty bummed, but am assuming I got the wrong product. Or I misread the recommendations. I'm not sure. Is this aragonite sand?

Can anyone suggest a sand that won't change my pH? Not looking forward to scooping all this out.

Thanks!

Hi everyone,

It is important to remember that to get the true pH of tap water it needs to sit in an open glass container for 24 hours to "de-gas" and remove the dissolved gasses (like CO2 which would cause the water directly out of the tap to read lower than it actually is). "De-gassing" is not necessary to do with well water but it is with municipal water. -Roy

 

Thanks for the drive-by post, but this was mentioned in the thread weeks ago - and was not the issue. I did indeed test de-gassed water.

@jaemiller, my original KH started out at 0-2 dKH (the first drop on an API test kit changed the color). Now I buffer to 3 dKH and have a pH of about 6.7 prior to C02 in the morning.

 

I'm setting up a new tank and put in HTH pool filter sand from Ace hardware after reading that many hobbyists had used it with success. At least, I thought I did. My pH is now over 8, verified by my monitor and my test kit. My tapwater is dead neutral.

Here's the one I got:

View attachment 1048357 View attachment 1048356

I just noticed that this package is labeled "compatible with salt systems," and also saw the water parameters on the back. So, I'm pretty bummed, but am assuming I got the wrong product. Or I misread the recommendations. I'm not sure. Is this aragonite sand?

Can anyone suggest a sand that won't change my pH? Not looking forward to scooping all this out.

Thanks!

I know this post is older but I’m happy to have found it. I set up a 75 gallon planted tank about a month ago. 3 pieces of bog wood, potting soil with a sand cap CO2 injection with solenoid controller. I use RODI water and re-mineralize with Salty Shrimp because my well water is difficult. I also used pool filter sand and and did not rinse it because it was really cold out. I too now have between a 7.9-8.1 pH. All other parameters seem good. I plan on following what you did with water changes but it is really interesting. Are you still good on pH?