PDA

View Full Version : Limestone to buffer PH?



madametechie
11-04-2013, 06:49 PM
I have a fairly well established planted 55 gallon aquarium with 4 large angelfish, 5 pearl gouramis, 1 large placo, and 2 giant danios (don't ask). I have a nice compact florescent light, substrate for plants, DIY CO2 and I fertilize. I already have several nerite snails and would like to have more. The problem is the water is not hard enough for the snails' shells. I've added some baking soda which brings the ph up to around 7.5 without the CO2, but the ph drops to 6.5 with the CO2 going. I've read that I can add limestone or crushed coral to my filter to help increase hardness and ph. Anyone have an idea how much? I have a magnum 350 canister filter. Thanks for your help!

byork
11-04-2013, 07:21 PM
Are you trying to increase your pH or raise your carbonate hardness? Putting limestone, marble, or crushed coral in your filter will increase your carbonate hardness which will increase your pH. What is your carbonate hardness?

AShin
11-04-2013, 07:32 PM
Those calcium rich feeder blocks they use at the shops are what i'd go too. It's a sure way to introduce calcium, as i've heard for scientific experiments with snails the only additive is some sort of calcium. In my setup i just crush the feeder blocks up which i think are 40% calcium and sprinkle it into the tank.

HN1
11-04-2013, 07:38 PM
Are you trying to increase your pH or raise your carbonate hardness? Putting limestone, marble, or crushed coral in your filter will increase your carbonate hardness which will increase your pH. What is your carbonate hardness?

That. Don't confuse pH for "hardness" and its usually better to aim for stability than a specific number.

Demonfish
11-04-2013, 09:59 PM
I would put some, maybe 10-20%, in the carbon container of the 350 and see what happens. It will slowly dissolve and raise the kH which will raise and stabilize your pH. When it gets too small, it could get through the screen and end up in your impeller well, so inspect and possibly replace it when you clean the filter. I expect your pH might creep up to about 7.5, or it may stay in between. I suggest a TDS pen or a kH test so you can keep an eye on your numbers.

AShin
11-04-2013, 10:13 PM
OO also don't rule out the elecrtolytes. Lawl~ I use mannapro but very sparingly. My water is pretty solid at 100tds pulled from the tap. I'm not sure how it'd work out but for osmotic balance reasons if electrolytes are missing altogether then you have a bigger problem than not being able to keep snails!

byork
11-05-2013, 06:10 AM
Where do you live? Why are you buffering your pH with baking soda with angels? I have nerites they do fine one tank has a couple the pH is about 5 and kH about 3. The other is about 6.5,4, respectively. They do fine their shells are not soft and they have been there for at least a year, they were in a different tank before that. They lay little white eggs everywhere and eat stuff. I am not trying to breed them but that wouldn't workout with the fish I keep anyway. I guess I am confused....I get that way. If you are trying to breed them you will need a new setup. Since crushed coral, limestone, and marble are all the same basic thing, calcium carbonate, and baking soda, sodium bicarbonate, are 2 totally different things you use them for two entirely different purposes. Even though they will both buffer your water but I don't think that is your real goal. If you are injecting carbon dioxide you are adding a week acid to your system, carbonic acid. So if you add the calcium carbonate the carbonic acid will slowly dissolve the CaCO3 and free the calcium into solution. This will raise your TDS, kH, gH and pH but all of these things tell you completely different things about the chemistry of your system. If you add the CaCO3 I would back off on the NaHCO3 because you won't need that buffer anymore, not sure you needed it. I would keep in mind what Ashin said about osmotic balance you could end up with a mess.

Demonfish
11-05-2013, 11:09 AM
I agree, if you use calcium carbonate, you don't need baking soda. And use it carefully as carbonate is a stronger anion (raises pH more) than bicarbonate. Esp. with CO2, you should have a way to measure kH, gH and pH so you can manage your chemistry safely.

madametechie
11-06-2013, 05:22 PM
Thanks so much for addressing my problems! My current ph is 6.0 kh 2 and gh 2. I began adding the baking soda because when my plants were looking weak, I turned back on my CO2 generator. When I did that, the ph plummeted to 5 and the fish weren't moving (I almost killed fish in the past with a ph crash). So, that's when I began researching about adding the baking soda. Then to combat the algae I was going to add about 50 nerites. I am also using a fertilizer called Yamato Green. I live in Cumming.

byork
11-06-2013, 08:05 PM
I looked up the Yamato Green - "for the average planted aquarium. Provides a rich source of chelated iron, potassium, magnesium, manganese, zinc, boron, sulfur, copper, vitamins and plant auxins (growth regulators), and other essential nutrients. Contains no phosphates. It is intended for planted aquariums with average fish loads."

Interesting product. Plants need K, P, and N to live they are Marco nutrients. This product offers K and other necessary micro nutrients. You need balance between phosphates and nitrates. Not sure you are adding those. I dose KNO3 to get adequate nitrates and I keep a heavy bio load. If your plants don't have the nutrients they require to use the co2 then the co2 will build in your system as carbonic acid causing a pH crash. Crushed coral will help this. Baking soda will also buffer but plants really don't benefit from the addition of sodium. They do benefit from the addition of calcium. Not sure what you test for on a regular basis but I test for nitrates, phosphates, kH, and gH. I have a spreadsheet I use to determine the appropriate dosages for my system. I use dry fertilizers so it may not fit exactly but I could share it. I based it on the estimated index but made modifications based on measurements and ideal values. I want to add losses due to uptake (so I don't have to test so frequently) but that seems to have to many variables for me to solve in my spare time.

Anyway the point is you need a source of nitrates, and phosphates (usually provided by fish feeding practices). So you probably need to test and dose kno3 as appropriate. In addition to the dosing you are currently doing (not including the baking soda) and the addition of CaCO3. Pm me if you want the spreadsheet.

madametechie
11-07-2013, 10:13 AM
So, unlike a non-planted aquarium, I SHOULD have a nitrate reading when I test my water? I did figure that the fish and feeding were providing adequate nitrates and phosphates. I guess if the ph continues to drop that would mean i don't have enough nitrates?

byork
11-07-2013, 05:00 PM
I am no expert but all aquariums that are cycled should have 0 ppm ammonia (NH3), 0 ppm nitrites (NO2), and >30 ppm nitrates (NO3). Some may recommend >20 ppm nitrates and it may depend on the fish you are keeping. I like to keep my NO3 about 10 ppm. It is possible to have a zero NO3 reading in a cycled planted tank, but this would indicate that the limiting nutrient would be N. Usually in my case it is K. If the tank is provided an extra source of N, like KNO3, then N would not be limited which should allow the plants to use other bioavailable nutrients. Really any cycled tank will have a NO3 reading.

The addition of KNO3 in to your system will not buffer your water. However, if the plants are able to use the bioavailable nutrients then their photosynthesis will be more effective, basically upping their metabolism, which will in turn cause you to have a higher concentration of free oxygen (DO) in the water. Once your DO has reached a saturation point then you observe pearling.

I just tried to write up in plain language how all the disassociation and chemical reactions work but it didn't make since so I am not including it. If you would like to see the chemical reactions written out, as chemical equations, I can post that. If it will help you understand.