# Raising pH with limestone



## joescaper1 (Feb 14, 2013)

Hello Everyone,

My ph is somewhat low out of the tap (below 7). I am not going to add chemicals, although I do use epsom salt, but would like to raise the pH with limestone.

I perform water changes (approximately 20%) weekly. If the fish reach full size, the tanks will be stocked at <1" of fish per gallon. The filter flow is rated at 10X per hour. I change water on Sunday with water from a storage tank filled the previous Sunday. I filter this water with a Magnum 350 to remove rust since I draw it pre-softener. The return flows through a basket of activated carbon to remove chlorine and any other chemical impurities.

The rockwork in one tank is red granite, the other red and black slate. In both cases limestone just doesn't look like it belongs there, so I would rather not include limestone in the tanks.

Now my question. Is it better to put the limestone in the sumps or is it better to put the limestone in the water storage tank to get the best results? By best results I mean avoiding any pH shock and resulting stress to the fish.

Thank you.
Joe


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## zimmy (Aug 13, 2010)

Limestone is not going to make a huge difference to your pH. Assuming you have fish that need a high pH, adding baking soda is a much more effective way to raise pH. I used it to raise my 7.4 pH to a pretty steady 8.2.

This is a good article.

If you go this route, you want to raise the pH slowly so you don't shock the fish.



joescaper1 said:


> I filter this water with a Magnum 350 to remove rust since I draw it pre-softener. The return flows through a basket of activated carbon to remove chlorine and any other chemical impurities.


I would just use a water conditioner (like Prime) to address issues around chlorine and any heavy metals in your tap water.


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## triscuit (May 6, 2005)

Limestone, crushed coral, aragonite, etc- will not raise your pH quickly enough- it's poorly soluble in pH-neutral water, at least in the time scales we're interested in. Folks see an initial bump in pH from the fine particulates of the new media, but it doesn't keep dissolving at the rate needed to maintain steady pH during water changes.


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## joescaper1 (Feb 14, 2013)

triscuit,
I decided to put the limestone in the holding tank to avoid any drops in pH due to water changes. Even if it is not very efficient, any upward correction is better than none.

This spawns another question: If it is not effecient, then what is the infatuation African cichlid hobbyists have with Texas Holey Rock? My understanding is that it is just drilled limestone.

Thank you.
Joe


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## triscuit (May 6, 2005)

THR is for looks. It's naturally formed honeycombed limestone, and it does nothing for water quality. Adding limestone to your holding tank will not "avoid any drops in pH due to water changes"

What we really need to know here is what your buffering capacity is. If you don't have a KH test kit, it's time to get one. What fish are you planning on keeping? If they are from the Rift Lakes, you are going to have modify your pH, hardness and buffering.


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## triscuit (May 6, 2005)

THR is for looks- it's naturally formed honeycomb limestone that has no effect on water quality. Pretty much the same thing as your limestone. :wink:

It's time to talk about what fish you are keeping, and what the buffering capacity of your water is. If you do not have a KH test kit, I highly recommend getting one now. Limestone in your holding tank will not "avoid any drops in pH", and if you are keeping Rift lake cichlids, you will need to be more proactive about maintaining steady (if not ideal) conditions. Baking soda is quick and easy... but you need to get that test kit to understand what water quality factors you are monkeying with.


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## joescaper1 (Feb 14, 2013)

triscuit,

Since limestone does not appreciably raise the pH, my entire premise is wrong.
In all the articles I have read, I do not recall seeing why the pH in Lake Tanganyika is high. I had assumed it was limestone. Could be diatoms I guess. I am going to have to do some reading outside of aquarium literature.

Thank you for your time and insight.
Joe


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## triscuit (May 6, 2005)

Time. Given geologic time, water will come into equilibrium with the local geomorphology. So, your understanding of equilibrium concentrations is fine, except that it takes centuries, not minutes, for water to dissolve sufficient amounts of calcium carbonate. Natural systems, like that of the rift lakes, have a water residence time of several hundred years... that means a drop of rain entering the lake will stay there on average for hundreds of years before flowing out or evaporating. Water changes in the aquarium also are of much higher percentage than any natural event (floods, storms, etc), and finally, your bioload in a confined glass box is incomparably higher than the bioload in the lake. The organic acids from food, poop, and respiration will drop your pH very quickly in your small, closed system... that's why buffering is so important.

I hope that clarifies a bit...


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## oyster dog (Jul 2, 2013)

Diatom shells are made of silica, not calcium carbonate.


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## triscuit (May 6, 2005)

Doh! ... good thing they can't take away my degrees, eh? I'm going to exercise moderator privilege and edit myself. 

Of course, diatoms make silica shells, which can be incorporated into limestone. The calcium carbonate in limestone comes from other aquatic invertebrates.


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## SupeDM (Jan 26, 2009)

I would have to agree with the previous posters and also disagree at the same time. In your water Limestone wont help with PH in any significant manner. Now just try to get that water soft and acidic with the limestone in it. Limestone will act as somewhat of a buffer preventing water from getting acidic. The water will have little chance of becoming and staying a PH below 7 with the limestone in it. In water above PH 7 there is very little if any reaction with the limestone. In water below 7 that reaction increases dramaticly. The main trick here isnt to have the perfect PH but rather to maintain a stable PH. Test your tap water after it has been sitting in a clean pail with an airstone for 24-48 hours. Whatever this PH reading is should be your target PH. Now try to find fish that thrive at that PH or are Hardy enough to adapt to it and you will be fine. Even Discus can be kept at high PH in harder water. As long as it is stable. They most likely will not breed and it isnt Ideal for them but it can be done successfully. My water out of the Tap is 7.4 PH with hardness In GH and KH off the top of any test kit i have ever owned. I have bred soft water south american cichlids and the more finicky Tanganyikan cichlids that need Much higher PH in this water for years.


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## SupeDM (Jan 26, 2009)

On another note if your GH and KH arent high enough for the fish you want to keep invest in a RO/DI system find an aquarium club near you sell the RO water to marine and Discus keepers and use the waste water to fill your storage tank. This waste water will have a much higher TDS than the regular tap water.


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## joescaper1 (Feb 14, 2013)

triscuit,

A couple of days ago, when you asked about my tank situation,I typed this out and it failed to post. I did not feel like typing it out again, so you got a short no information reply. Here is attempt two. Probably more than you ever wanted to know.

I have been keeping Tanganyikan cichlids continuously (N. brichardi has always been a part of it) for the better part of four decades (1975); the last 25 years at my current residence. Until recently I never paid any attention to water parameters. I have used under gravel filtration with power heads throughout. A long time ago I had a complete tank die off due to my N. brichardi (they were L. brichardi when this happened  ) cleaning all the gravel off of the plate underneath the rockwork. A solution has been put in place to prevent this from happening again. I had a heater malfunction kill off a tank as well. I now have a sensor shut off the power to the heaters if the temperature rises too high (it works when I test it in hot water I just hope it works when needed). Currently I have brichard in one tank(red granite rockwork), J marlieri, N. leleupi and T. sp. Red Moliro, in the other(red and black slate rockwork). All are less than one inch of fish per gallon.

A year back my wife accompanied me to a swap meet. She announced that she wanted me to set up a discus tank in the dining room. I read a lot of articles on discus care. When I told her how much it was going to cost she said forget it. However, the ideas of flow rate and wet/dry filtration caught my attention. I built my own wet/dry filter system by modifying systems from "You Tube". The flow rate is around 7X tank volume per hour from the wet/dry and 8X tank volume per hour from the under gravel.

Included in the reading was a lot of opinion on pH. Consensus is that, it does not really matter what the pH is, as long as it is consistent. I went out and bought the pH test strips. The water in my tanks (I have two) and the water from the source, tested at <7. I thought that raising it a bit might make the fish show better color or behave a bit differently; hence the question about limestone. Through all these years, spawning occurred regularly. I do not have grow out tanks so spawns never survived, so I do not know if the lower pH affected male/female ratios or if it had anything to do with survival rate.

I have been in an electroplating operation for 40 years, so I understand there is a balance that needs to be maintained when adding chemicals to adjust pH. Wild pH swings manifest when imbalances occur. I also know I have to monitor that situation twice daily. I do not want to do that at home, so no chemicals. I do add Epsom salts to the tank, but that is out of habit, I have been doing it since the beginning. Rift lake salts were rather expensive when I was a kid and Epsom salt (dirt was more expensive  ) was the accepted substitute.

I do have one question for SupeDM. What dissolved solids from the reverse osmosis/deionized water system waste would be beneficial to an aquarium? I would think there would be some chlorides, fluorides and undesirable metals present in higher concentrations.

Joe


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## triscuit (May 6, 2005)

Adding baking soda is just as as simple as adding Epsom. Epsom is all I've used to increase hardness too. When getting local tank raised fish that haven't been kept in pH > 8 water, you'll be fine. However, fish kept under conditions they evolved to thrive under are better looking and more disease resistant than fish kept in less than ideal conditions. That you want better color and more stable water parameters is good- and the solution is very simple: baking soda.


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## SupeDM (Jan 26, 2009)

Yes there would definately be a need to filter the waste water from the RO/DI with carbon to rempve the unwanted impurities. However the calcium, magnesium and other minerals that are present in tap water would be more concentrated since the RO/DI systems filter this out.


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## joescaper1 (Feb 14, 2013)

triscuit, zimmy, SupeDM,

I will use baking soda to raise the pH of the water change storage tank.

Thank you all.
Joe


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## joescaper1 (Feb 14, 2013)

zimmy, triscuit, SupeDM,

I will use baking soda raise the pH in my storage tank.

Thank you all.
Joe


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