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Discussion Starter · #1 ·
Hey guys, first post here, so be easy on me. ;)

My question is about cutting my R/O water with my tap water and also lowering the PH (seems difficult). My tap is 7.5ph, 9 GH, and 7 KH. I would like (I think) to have below 7 PH and GH at about 4-5 and KH at about 3 or so. Anyway, I can easily adjust the hardness by cutting the R/O water with tap, but my PH is another issue as what I am learning is that it bounces back up. So what to do? Not worry about it so much, as it will fluctuate with CO2 anyway? I know I can do it with peat and such, but I really don't want to have to mess with that if possible. I don't want to use R/O completely if I don't have to, as I might as well use the free stuff, right? I think maybe a 50/50 split is fine if I can get my PH to stay down.

Background:
I have a planted 29 gallon tank with a CO2 reactor with a solenoid. Stocked with a school of curently 12 Cardinal tetras. Fluval canister filter with a Fluval Plant Spectrum LED. Amazon Sward, hygrophila, and Anubias Barteri. I am about to order a bunch more plants and probably replace some of what I have. Also, I have had a large piece of grapevine that I will soon put back into the tank, I didn't treat it properly the first time and caused problems.

Oh yeah, I've been in the hobby for quite some time, but new to the CO2 injection. (kind of)
 

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Hi @Scheidtman

Welcome to TPT!

The high pH, dKH, are directly related to the carbonates (typically calcium carbonate) dissolved in your water (as is dGH to a lesser degree). I suggest using a very, very small amount (i.e.one (1) drop per 20 gallons) of muriatic acid (dilute HCl) to convert the calcium carbonate into calcium chloride. Reducing the amount of carbonates will lower the pH and dKH and to a lesser degree the dGH. I dose once, wait 24 hours, then check pH & dKH and dose again if necessary. Make sure you have no rocks; stones, substrate that is causing the pH, dKH to increase. Anything with limestone like coral, shells, some gravels, local stones, and Seiryu stone just to name a few sources of calcium carbonate we may have in our tanks. -Roy
 

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Not really sure what your question is?

You can easily lower dKH by mixing with RO. 50/50 mix with dKH 7 water will get you to 3.5 dKH.

When you say that the pH bounces back up, what do you mean?? Do you have something like Seiryu stone in the tank that is raising it? If not pH does not rise.

In the bigger picture, in my opinion if you are going to the trouble of making RO you might as well go 100% RO.
 

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Discussion Starter · #4 ·
Not really sure what your question is?

You can easily lower dKH by mixing with RO. 50/50 mix with dKH 7 water will get you to 3.5 dKH.

When you say that the pH bounces back up, what do you mean?? Do you have something like Seiryu stone in the tank that is raising it? If not pH does not rise.

In the bigger picture, in my opinion if you are going to the trouble of making RO you might as well go 100% RO.
My question is about the PH, specifically. What I mean about the PH bouncing back up is when I mix say 50/50 RO/Tap, the initial PH is lower, but then it seems to bounce back up if left in the bucket until the next day. As for not going 100% RO, by nature I don't like to pay for something I can get for essentially free, so why purchase minerals to add back into the RO water when I can just mix with tap water to get the same results. That's all I'm saying. That being said, I do have Seachem Equilibrium if I wanted to go straight RO, but I'm trying to learn to be smarter. :)

As for the stone that I want to put in the tank, I suppose I'll test it by submerging it in some RO water and see if it leaches anything overnight.

Hi @Scheidtman

Welcome to TPT!

The high pH, dKH, are directly related to the carbonates (typically calcium carbonate) dissolved in your water (as is dGH to a lesser degree). I suggest using a very, very small amount (i.e.one (1) drop per 20 gallons) of muriatic acid (dilute HCl) to convert the calcium carbonate into calcium chloride. Reducing the amount of carbonates will lower the pH and dKH and to a lesser degree the dGH. I dose once, wait 24 hours, then check pH & dKH and dose again if necessary. Make sure you have no rocks; stones, substrate that is causing the pH, dKH to increase. Anything with limestone like coral, shells, some gravels, local stones, and Seiryu stone just to name a few sources of calcium carbonate we may have in our tanks. -Roy
Thanks for the HCL tip, I happen to have some of that which I used in my pool this summer. It's EXTREMELY strong stuff, so I know what you mean by one drop per 20 gallons, it took barely anything to lower my entire pool PH. So, if I understand you correctly, I could actually collect straight tap into my 18 gallon bucket and lower the KH and PH with a certain amount of drops of HCL?
 

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Hi @Scheidtman

Test your water parameters.

Add one drop of HCl, stir, let sit 24 hours

Stir again and then check water parameters

You will eventually find the dose that works for you.

-Roy
 

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Your tap water has some CO2 in it. That is very common.

Your pH is rising as the CO2 dissipates and the water comes to equilibrium with the atmosphere. Perfectly normal.

To get a fully degassed sample, leave out a glass of the 50/50 mix for about three days, or one day with vigorous bubbles. Then begin testing pH about every 4 hours. Once the reading stabilizes then that is your degassed pH value. It should correlate to your dKH.

In my opinion there is no reason for you to fool around with HCL. You already have the safest and best way to bring down pH with RO water.
 

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Discussion Starter · #7 ·
Your tap water has some CO2 in it. That is very common.

Your pH is rising as the CO2 dissipates and the water comes to equilibrium with the atmosphere. Perfectly normal.

To get a fully degassed sample, leave out a glass of the 50/50 mix for about three days, or one day with vigorous bubbles. Then begin testing pH about every 4 hours. Once the reading stabilizes then that is your degassed pH value. It should correlate to your dKH.

In my opinion there is no reason for you to fool around with HCL. You already have the safest and best way to bring down pH with RO water.
[
QUOTE]

So what you're saying is concentrate simply on dKH and pH will find its equilibrium naturally, so don't worry about it? So basically I should just cut my tap water to bring it to whatever carbonate harness I want and not worry about the pH?
 

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So what you're saying is concentrate simply on dKH and pH will find its equilibrium naturally, so don't worry about it? So basically I should just cut my tap water to bring it to whatever carbonate harness I want and not worry about the pH?
When you cut your tap with RO it will bring down the dKH and hence the pH. If you are not adding any carbonates via dosing CO3 or adding stones that leach dKH it will remain stable once it comes to equilibrium.

You do want to measure your fully degassed sample as you want to target a pH drop from CO2 injection.

If the 50/50 mix brings your dKH to 3.5, then I would expect to see the fully degassed sample at about 7.4 to 7.5.

In your opening post you listed your dKH at 7 and your pH at 7.5. That is very unlikely and I would suspect that your tap still had CO2 in it when you were testing. If you were to fully degas a sample of tap water I would expect to see pH about 7.7 to 7.8.

The other wild card is your substrate. I am guessing it is inert. If it is active it would driving down the pH in the tank, and you don't describe that as happening.
 

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Discussion Starter · #10 ·
To what end are you trying to drop the ph of your water? Chasing ph is usually a waste of time, if you want softer water then just do the 50/50 mix.
Yeah, that's what I'm beginning to understand, pH isn't as critical as we once thought. I've been in the hobby for over 30 years, and back then there was a lot of emphasis on it. I haven't been doing my homework until very recently, when I decided to go higher tech.
When you cut your tap with RO it will bring down the dKH and hence the pH. If you are not adding any carbonates via dosing CO3 or adding stones that leach dKH it will remain stable once it comes to equilibrium.

You do want to measure your fully degassed sample as you want to target a pH drop from CO2 injection.

If the 50/50 mix brings your dKH to 3.5, then I would expect to see the fully degassed sample at about 7.4 to 7.5.

In your opening post you listed your dKH at 7 and your pH at 7.5. That is very unlikely and I would suspect that your tap still had CO2 in it when you were testing. If you were to fully degas a sample of tap water I would expect to see pH about 7.7 to 7.8.

The other wild card is your substrate. I am guessing it is inert. If it is active it would driving down the pH in the tank, and you don't describe that as happening.
Yes, I have been testing the pH of the water right out of the tap, but I will let it degas and test. The water in my tank is close to 7.00. I have clay substrate and have always had driftwood in the tank.

So what would you suggest I get my dKH down to for a planted CO2 infused tank with Cardinals? I was thinking around 3?
 

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Yeah, that's what I'm beginning to understand, pH isn't as critical as we once thought. I've been in the hobby for over 30 years, and back then there was a lot of emphasis on it. I haven't been doing my homework until very recently, when I decided to go higher tech.

Yes, I have been testing the pH of the water right out of the tap, but I will let it degas and test. The water in my tank is close to 7.00. I have clay substrate and have always had driftwood in the tank.

So what would you suggest I get my dKH down to for a planted CO2 infused tank with Cardinals? I was thinking around 3?
I'd save yourself the effort and just run the tap water as is first, and if you feel the need to have softer water you can always start adding some ro during water changes.
 

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Yeah, that's what I'm beginning to understand, pH isn't as critical as we once thought. I've been in the hobby for over 30 years, and back then there was a lot of emphasis on it. I haven't been doing my homework until very recently, when I decided to go higher tech.

Yes, I have been testing the pH of the water right out of the tap, but I will let it degas and test. The water in my tank is close to 7.00. I have clay substrate and have always had driftwood in the tank.

So what would you suggest I get my dKH down to for a planted CO2 infused tank with Cardinals? I was thinking around 3?
I don't keep Cardinal's so have no practical experience.

But in general fish are very adaptable and really don't care much about pH levels. I keep my Rainbows at zero dKH no problem. And most of the rest of the world has very soft water and keep a wide variety of fish.

Interesting you say your tank pH is 7.00. Is that with CO2 injection? A clay substrate is inert and should not affect pH at all.

What are you using to test pH? Calibrated probe?
 

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Discussion Starter · #13 ·
I don't keep Cardinal's so have no practical experience.

But in general fish are very adaptable and really don't care much about pH levels. I keep my Rainbows at zero dKH no problem. And most of the rest of the world has very soft water and keep a wide variety of fish.

Interesting you say your tank pH is 7.00. Is that with CO2 injection? A clay substrate is inert and should not affect pH at all.

What are you using to test pH? Calibrated probe?
Yes, I'm using a calibrated probe and also have a liquid test. Lately I have used the probe. I do inject CO2, but that's not when it's 7.0, I got that reading this morning. I had wood in there for a long time and also I have heard clay will drop the pH, but who knows. All I know is what I see. The dKH in the tank is 4, I don't use my tap water straight. In fact, all I've used until recently is R/O with additives. Actually, just straight R/O to replace the evaporated water. I didn't do much water changing for a while, since I barely had any fish in the tank and the plants were doing fine. Recently I started to play and added a CO2 system and fish.
 

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Yes, I'm using a calibrated probe and also have a liquid test. Lately I have used the probe. I do inject CO2, but that's not when it's 7.0, I got that reading this morning. I had wood in there for a long time and also I have heard clay will drop the pH, but who knows. All I know is what I see. The dKH in the tank is 4, I don't use my tap water straight. In fact, all I've used until recently is R/O with additives. Actually, just straight R/O to replace the evaporated water. I didn't do much water changing for a while, since I barely had any fish in the tank and the plants were doing fine. Recently I started to play and added a CO2 system and fish.
The pH reading in the morning is not the same as a fully degassed sample.

Tanks do not fully degas overnight.

My degassed pH is 6.25 but my tank measures about 5.80 in the morning.
 

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Discussion Starter · #15 ·
The pH reading in the morning is not the same as a fully degassed sample.

Tanks do not fully degas overnight.

My degassed pH is 6.25 but my tank measures about 5.80 in the morning.
So when should I take a PH reading from my tank to get fully degassed? I pump CO2 into it during the daytime hours, so that's not "fair" either. I figured the morning would be the most accurate. I'll take a reading now. Well look at that, 7.31. Interesting. I did do a 30% water change yesterday, so I wonder if I'm driving the PH up. I've decided a 2:1 RO/tap mix was good to give me about 3 dKH and 4 dGH, so I'm sticking with that.

...and currently there is no wood in the tank.
 
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