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Discussion Starter #1
I have a planted 135l planted tank. I have a canister filter.

My plan is to slowly replace my water with rodi water. The rodi water has a ph of 6.

I want to use coral chips to slowly increase the ph, gh and kh. I'm aiming for a ph of around 6.8 - 7. At the moment with my tank water I have a ph of 7.6 and kh of 2. Ive added 30litres of rodi water already.

I get my gh test kit in a day or so. Ill post that as soon as i test that. I have some seachem equilibrium but as i understand it coral chips does the same thing.

So my question is how do i slowly replace all my water with rodi water and maintain the minerals and ph because the ph probably wont drop enough for me to use the chips until most of the water has been replaced?
 

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You will likely need to use a fast-acting GH and KH booster before or as you add the water to the tank, unless you are doing very small water changes.

Coral chips raise GH/KH, but they do so *VERY* slowly. They are calcium carbonate, which dissolves rather slowly unless you are using something like straight hydrochloric acid.

If you do a 20% water change with RODI, your KH/GH will fall by 20% and take several days to recover. This is NOT a good thing for your fish to have your KH and GH dooing roller coasters.

Equilibirium will boost the GH, but will not increase KH.. you'd need something like baking soda, or alkaline buffer to do that part.

Are you sure you really want to replace with RODI?
 

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Discussion Starter #3
Ok. I have some seachem alkaline buffer.

Replacing the water with rodi is a good thing isnt it?

The main reason for wanting to go to rodi is so i can decrease the ph abd hopefully increase kh and gh. Plus the other benefits of reduced algae, reduced effect to changing ph in tap water and other things that might be in the tap water.
 

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Ok. I have some seachem alkaline buffer.

Replacing the water with rodi is a good thing isnt it?
IMO, not always. There's a lot of stuff you need to put back in the water to make it suitable for fish.

That said, using RODI is a good thing if you are certain you can end up with better water when you are done because your tap contains a large amount of something problematic.

Others may differ in this opinion, but many seem to be under the impression their tap water contains horrible things that their fertilizers, and GH/KH boosters do not. Many of these are, IMO, expecting their fertilizers and GH/KH boosters are free of contaminants out to the ppb level. Sorry, you are almost certainly adding the same trivial traces of lead, arsenic, pthalates, and other things to your tank in this process.



The main reason for wanting to go to rodi is so i can decrease the ph abd hopefully increase kh and gh. Plus the other benefits of reduced algae, reduced effect to changing ph in tap water and other things that might be in the tap water.
You can't really decrease pH and increase KH. Any KH booster you add will raise both KH and PH. The only way to decrease pH without affecting KH is to inject CO2.

But why are you trying to lower your pH and raise KH anyway?

Plus the other benefits of reduced algae
How does RODI reduce algae?

If your tank is planted, you have to add back all the things that are necessary for plants to grow: nitrate, phosphate, potassium, secondary and micronutrients, or your plants will die too. Algae is a plant, so once you've added this stuff back, it has all it needs. Trying to suppress algae through nutrient deprivation in a planted tank is an effort in plant suppression too.

Non-planted folks may seem some benefit from the reduced phosphates, although there are other ways to do this. Things like phosgard will also take out the phosphate added by your fish food.
 

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Unless you are doing native wild caught fish your tap water may be the same as the shop where you get the fish. Meaning this may be counterproductive as they may already be used to what you have for tap water.
Rams for example will be an exception to this if your tap is over 7 PH.
 

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side note, you might want to read Tom Barr's post (plantbrain) here:

http://www.plantedtank.net/forums/showthread.php?t=85179

Tom's the inventor of the EI dosing strategy many folks here use. He clearly has considerably more expertise in planted tanks than I do, and the same goes for most people.
 

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Discussion Starter #7 (Edited)
I will read thread when i get home from work But in the meantime what do yous suggest i do?

I have 7 guppies, 4 neon rainbowfish, 1 clown loach, 1 blovian ram and 1 rifle shrimp. Im going to need to remove the clown loach eventully.

My tap water at the moment has a ph of about 7.8. With all tap water in my tank my kh is about 3. Ill post my gh soon. I didnt mention i have root tabs in place already and flourish excel on its way.

Thanks for the help by the way.
 

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I'm not particularly experienced with Rams.. That said, my inclination is to do nothing at all.

That said, if you really need pH under 7, you either need CO2 injection or you need to take your KH down below 1.

I really don't get sites like this one:
http://www.liveaquaria.com/product/prod_display.cfm?c=830+889+1084&pcatid=1084

Which claims the GBR needs KH 5-12 and pH 5-7.0.

Even getting to pH 7.0 at a KH of 5 requires a CO2 concentration of 15ppm... That doesn't make any sense, as you can't get to 15ppm without CO2 injection...

So what do these fish really need? Neutral pH, or high KH.. you can't have both in a non-injected tank.
 

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So what do these fish really need? Neutral pH, or high KH.. you can't have both in a non-injected tank.
The relationship between pH, KH and CO2 assumes that bicarbonate is your primary (only?) buffer, which isn't always correct.

High levels of organic buffers (humic acids in blackwater), and phosphates will allow you to have a high buffering capacity at a low pH and low CO2.
 

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I am switching over to RO in my tank because my local water conditions vary wildly throughout the year, but this is not common for most people.. our municipal water comes from one of any of dozens of high altitude lakes and the parameters change suddenly without warning.. causing alot of stress to plants/fish.. it is easier to follow a nutrient calculator when I know that I am starting off at 0ppm, instead of guessing whats in the tap water this week. I tried it with tap water for a year now and its been rough, just when things are stable something changes.

I switched to RO for houseplants/orchids a few years ago and add back all the nutrients manually, they have been doing alot better and its much easier to setup and follow feeding charts.. trying to figure out wtf the tap water had done after the nutrients had been locked out was a pita. This is more work in general but less work on average.. I already have an RO system so I might as well use it is my attitude right now.

If you have stable tap water its much easier to just learn to adjust that if/as needed.. I had none of these problems before moving to the mountains.
 

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The pH and kH will reduce during nitrification processes. Im in Sydney too, my pH out of the tap is around the same and by the time I add CO2 etc. it is a pH of 6.
 

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im not the op @onefang, just chiming in that there are people whom need RO.. dunno what municipal water is like in Australia, might be really hard well water that needs filtering.

Right now I am using kent ro right but once this bottle is empty I am going to give equilibrium a shot because I could use the cal+mag... Arm and Hammer keeps my kH good and all macro and micro nutrients get mixed back in..

fish may survive a wide range of pH but plants will get nutrient lockout if it swings too far away from neutral.. go look at a pH nutrient chart, you can show deficiencies even with abundant nutrients just from poor pH.. plants that need a specific nutrient in abundance to thrive will need to be kept at a pH suitable for absorbing that nutrient.
 

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Discussion Starter #13
I could try peat But ive looked around and aparently it only softens water doesnt lower ph. If i do use ro water what do you think is the best way to do it and is equilibrium ok to remineralize?. I tried diy co2 but didnt end well. Pressurized co2 is too expensive for me.
 

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The relationship between pH, KH and CO2 assumes that bicarbonate is your primary (only?) buffer, which isn't always correct.

High levels of organic buffers (humic acids in blackwater), and phosphates will allow you to have a high buffering capacity at a low pH and low CO2.
Yes, you can have low pH and low CO2...

However, the original statement is you can't have both of the above *AND* a high KH, which explicitly means high carbonate content.

humic acids will lower pH, but they will also lower KH, like any acid other than carbonic acid.

Phosphate buffers will also lower KH, and GH, as they tend to cause calcium carbonate to precipitate. However, they present a strong buffer that isn't carbonate based, and thus using KH and pH to estimate CO2 with them will be misleading.. Even though the KH is low, the phosphates will buffer as if much more carbonate was present. That said, this still doesn't help you get low pH, high KH without high CO2.

So, do you know of a way to have all three? Low CO2, High KH and low pH??
 

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However, the original statement is you can't have both of the above *AND* a high KH, which explicitly means high carbonate content.
The name is carbonate hardness, but that is not what we measure when we use a KH test kit, nor is that what is important to fish health.

KH test kits measure total alkalinity, or more descriptively, the buffering capacity of the water. Simply put, it is a representation of the amount of acid required to drop the pH by a large amount. Low buffering capacity, and the pH is easy to decrease with acid. High buffering capacity, and the pH is not easy to decrease with acid.

Lots of things can act as a buffer to prevent pH drops, so you can have a high measured KH even if there is no carbonate in the water and the pH is low. In the context of an Amazonian blackwater fish like Rams, the KH comes from humic acids that are acidic but also contribute significant buffering capacity.
 

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Carbonate hardness is the name because what we are measuring is carbonate and bicarbonate anions. When we measure KH with a test kit, you are basically adding a indicator, and then adding an acid to the water until it overcomes the carbonates and the pH drops, at which point the indicator changes color. (in API's case, the indicator is mixed with the acid)
You can have other things act as a buffer besides carbonates as you've said - but that is not what we are measuring with a KH test kit.
Yes, that is exactly how the KH kit works, but you are wrong that it only measures buffering as a result of bicarbonate. Phosphate, other salts, and organic acids all contribute to the KH measurement.
 

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The name is carbonate hardness, but that is not what we measure when we use a KH test kit, nor is that what is important to fish health.
Fair, I understand that some KH test kits are actually acid-titration tests for measuring alkalinity, and are technically not KH tests at all, they're just alkalinity tests calibrated to a KH scale.

That said, if sites like LiveAquaria really mean alkalinity, they should say alkalinity, not KH. No, really, this is a technical hobby, we can do without the lies. API should probably also stop marketing their tests as KH, because that's not what they are actually testing either.

As it stands, that site is explicitly asking for KH, which and the OP in this thread was specifically trying to lower pH and raise KH. That is still fundamentally not possible.

If you want to change the terms to be "has sufficient alkalinity to read as if it were 5 dKH on an API titration KH test", well that's a different mater entirely.

So again, what do GBR *really* require, so we can help the OP? Do they require pH under 7? Do they require high alkalinity? Do they require carbonates?
 

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No, really, this is a technical hobby, we can do without the lies. API should probably also stop marketing their tests as KH, because that's not what they are actually testing either.
All true. Pretty much everyone uses KH believing that it means just carbonate, but they really mean total alkalinity or buffering capacity.

As it stands, that site is explicitly asking for KH, which and the OP in this thread was specifically trying to lower pH and raise KH. That is still fundamentally not possible.
That site is technically wrong, API is using unscientific marketing, and most people in the hobby are complicit in the confusion. In most cases it doesn't make much difference because carbonate is the primary buffer, but this is an obvious exception. So......

what do GBR *really* require, so we can help the OP? Do they require pH under 7? Do they require high alkalinity? Do they require carbonates?
...... my interpretation would be that GBR probably require a low pH that is very stable, which is achieved by high alkalinity. The way to do this without CO2 would be to use peat or blackwater extract, which exactly matches their natural habitat. It drops the pH and keeps what we measure with a KH kit high.

Bump:
Not to totally derail..
Its all good!

On a side note - you can actually mess with pH without influencing the alkalinity reading by adding NaOH to the water - but I think this would do the opposite of what the OP wants.
Yeah, if we still assume carbonate is the dominant buffer, this works great for bringing the pH up without increasing alkalinity. But you always have a lot more trouble bringing it down because the equivalent acid, something like HCl, will just cause the carbonates to turn into CO2. pH goes down, KH plummets, unstable tank.

As a random musing, I've always wondered whether the acid forms of biological buffers like Tris, HEPES, MOPS etc. etc. would work well in an aquarium.

*

In any case, I think that the best conclusion was reached earlier in the thread. Don't mess with your pH unless you REALLY have to, or understand exactly what you are doing.
 

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As for what the fish want, I would go by the GH of their natural water. (Moderate, not too soft for most of these.)
Then set the KH about equal to that.
Let the pH do whatever it will, it is the least important of these.

The best Guppies I ever had were in low end brackish tanks. Not soft water fish.

The other fish you list are from softer water, but not very soft.
http://www.fishbase.org/summary/Mikrogeophagus-altispinosus.html
http://rainbowfish.angfaqld.org.au/Praecox.htm
http://www.loaches.com/species-index/clown-loach-chromobotia-macracanthus

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Lets approach this the other way:
What are the test results for your tap water?
Is there anything toxic in there in such levels that you do not want to use it for your tank?
Is the quality consistent enough through the year that you can do a water change without having to test the new water very often?

If you have reasonably good tap water, then use it.
If it is too hard (high GH, KH, TDS) for the fish, then blend with RO. Peat moss is optional.

If your tap water is unusable (like nayr's) then look into RO.
 
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