Who Gives A Fish Forums

I'm having a tough time getting my water chemistry to match Lake Tanganyika's. My tap water is 7.8 pH with a gH of 4 deg.

I've managed to bump up the gH to 11-12 using a mix of play sand, crushed coflake, snail shells, and Mindwave. The pH has gone up slightly to 8.0, but I'm not expecting Mindwave to change it much since it's sulfate-based.

This website I found has some interesting info. Apparently, most of Lake Tanganyika's carbonate comes from magnesium, not calcium. In fact, Malawi has more calcium, but lower pH and gH. It seems like magnesium carbonate is what gives Tanganyika its alkalinity. Plus, Tanganyika has way more potassium, sodium, and chloride than Malawi.

Since Mindwave won't change the pH, I think I need something that'll dose carbonates. I'm guessing I'll want more magnesium carbonates than calcium. Should I also add some salts to boost the potassium, sodium, and chloride levels? Any suggestions on products that can help me with this?

I've had my fair share of experience with Mindwave, and I gotta say, it's not the best solution for replicating the water chemistry of Lake Tanganyika. I recall discussing this with Seachem a few years ago, and they made it clear that while it may raise the GH, it's not reliable for meeting the needs of your fish - it's more geared towards plants.

You've got two viable options to consider. Personally, I'm a fan of using a calcareous substrate, which is specifically designed for rift lake conditions. I've used aragonite sand in the past, and it's been a game-changer. However, you do need to be mindful of water changes, as introducing a large amount of soft water can be problematic for your fish.

The alternative is to use rift lake salts to prepare the water. These aren't your typical sodium chloride salts, but rather mineral salts designed to replicate the water chemistry of the rift lakes.

In terms of pH, you don't need to stress too much about hitting a specific number, as long as it's on the higher side - we're talking high 7's and up. Adding substances like coflake can help raise the pH, but it won't have a significant impact on the GH. I've tried this approach before, and it's not the most effective way to go about it.

Dead coflake skeleton or rubble, as well as limestone and shells, will raise the pH to 8.5. I've had some experience with this in my own tanks.

I'm actually pretty sure Lake Tanganyika has more calcium than magnesium, not the other way around. The chart on the link provided seems a bit confusing, listing 'Total hardness as calcium carbonate', 'Total calcium as calcium carbonate', and 'Total magnesium as calcium carbonate'. I'm not convinced this is entirely accurate, as magnesium and calcium are different compounds.

I've used the Aquasonic Rift Lake conditioner in my own Rift Lake tanks, and also to increase the GH for my rainbowfish. The ingredients include sodium chloride, sodium carbonate, magnesium chloride, magnesium sulphate, calcium chloride, calcium sulphate, potassium chloride, potassium nitrate, lithium chloride, sodium bicarbonate, and sodium thiosulphate. I found the directions for use to be somewhat misleading - adding one level teaspoon per 7 liters of water didn't quite work for me.

What I found more effective was to first work out the GH of my water, add the conditioner, and then test it again 24 hours later. If you have hard water to begin with, you don't need to add as much. On the other hand, if you have really soft water, you might need to add more. It's also worth noting that Rift Lake salts need to be added to a container of water and aerated for 24 hours before using the water in a tank containing fish.

Sodium thiosulphate is used to neutralize chlorine in water, which is why it's often found in dechlorinators. Anything with chloride at the end will increase the GH, while anything with carbonate or bicarbonate will raise the KH and pH. As for potassium nitrate, I'm not entirely sure what it's meant to do for fish - I've only ever associated it with making bombs and gunpowder. Now I just imagine my shell dwellers throwing bombs at each other.

I think it's worth considering a balanced approach. For me, using an inert substrate and adding rift lake salts is the way to go. This way, you have complete control over the water parameters and don't have to worry about large water changes causing issues.

I've had my share of frustrations with Seachem products. They seem to want you to buy a whole range of products, which can get expensive. And let's be honest, who wants to do complex calculations every time you do a water change? I learned the hard way when I bought their Equilibrium product for a specific tank. I soon realized I also needed pH Up and pH Down, and working out the ratios was a nightmare. I ended up ditching it all and switching to mineflake salts, which have been a game-changer. I simply add the same amount to every bucket, and my water parameters are always spot on.

I also had issues with the Equilibrium product making my water cloudy, despite their claims that it would dissolve completely. Needless to say, I won't be using their products again anytime soon.

As for pH, I think it's overrated. If you get your GH and KH right, your pH will automatically fall into a suitable range. The actual value doesn't matter as much as people think.

I'm finally starting to grasp this water chemistry thing. I used to think KH was just a part of GH, but that's not the case. GH measures the metal ions like potassium, magnesium, sodium, and calcium, which are essential for plant growth. KH, on the other hand, is specifically about the carbonate levels. Adding calcium doesn't raise the pH unless it's in carbonate form - it's the carbonate that removes hydrogen ions from the solution, not the metals. So, if you add calcium carbonate, you're raising both GH and KH because you're adding metal cations and carbonate anions. However, due to the relative weights, you're probably adding more carbonate than calcium, which means the KH increases more than the GH.

I'm starting to think that the exact amounts of calcium and magnesium aren't as crucial as getting the KH, GH, and pH close to Lake Tanganyika's parameters. It's likely not a big deal how much of the GH comes from calcium versus magnesium. My local water supply probably has a higher KH than GH, which acts as a pH buffer. I've got a 29-gallon blackwater tank with loads of decomposing leaf litter and wood, and despite the tea-like appearance, the pH is still 7.8, the same as the tap. This is likely because the carbonate in the tap is maintaining the pH. I'll have to measure it to confirm, though.

I think I'll just get a Tanganyikan-specific buffer and ditch the Mindwave, which is really only useful for plants due to its lack of carbonate.

I've found that my go-to salt mix effectively raises GH and KH in my tanks. The ratio is roughly 2:1, so for my specific needs, I add one teaspoon to 10 litres of RO water to achieve dGH 6 and dKH 3. If I need to boost it further, doubling the amount gets me to 12:6. My shrimp tank, with this setup, maintains a pH of 7, while the softwater RO tank hovers at 6.5 - I don't intervene with either.

I've opted out of using tap water due to its hardness and high nitrate content of 50ppm. One thing to keep in mind when increasing KH is the potential for more limescale buildup, but it won't significantly impact your GH, and your water will remain alkaline, which is ideal.

GH specifically measures divalent metal ions, primarily calcium and magnesium, but also smaller amounts of other metals. It's expressed as if all the metals were calcium carbonate, which is why you often see it referred to as 'as mg/l calcium carbonate'.

I've learned this from my son, a PhD chemist who used to work for a water testing company. He's explained to me that sodium and potassium are monovalent, so they're not included in GH, and neither are trivalent metals like aluminium.

KH, on the other hand, is a measure of the buffer in the water, mainly carbonate and bicarbonate. However, it's not directly measured as carbonate; instead, it's determined by adding acid until the pH drops to 4.5. My son has told me that some water companies use the term 'alkalinity' instead of KH, which can be a bit confusing.

angelica wrote: ↑Fri May 02, 2025 3:15 am I think it's worth considering a balanced approach. For me, using an inert substrate and adding rift lake salts is the way to go. This way, you have complete control over the water parameters and don't have to worry about large water changes causing issues.

I've had my share of frustrations with Seachem products. They seem to want you to buy a whole range of products, which can get expensive. And let's be honest, who wants to do complex calculations every time you do a water change? I learned the hard way when I bought their Equilibrium product for a specific tank. I soon realized I also needed pH Up and pH Down, and working out the ratios was a nightmare. I ended up ditching it all and switching to mineflake salts, which have been a game-changer. I simply add the same amount to every bucket, and my water parameters are always spot on.

I also had issues with the Equilibrium product making my water cloudy, despite their claims that it would dissolve completely. Needless to say, I won't be using their products again anytime soon.

As for pH, I think it's overrated. If you get your GH and KH right, your pH will automatically fall into a suitable range. The actual value doesn't matter as much as people think.

Thanks for the info, essjay. 50ppm of nitrates in tap water does seem pretty high. I'm lucky my water supply has 0 ppm for ammonia, nitrite, and nitrate. I guess that's one thing to be grateful for.

florapod wrote: ↑Thu May 01, 2025 11:07 pm I'm having a tough time getting my water chemistry to match Lake Tanganyika's. My tap water is 7.8 pH with a gH of 4 deg.

I've managed to bump up the gH to 11-12 using a mix of play sand, crushed coflake, snail shells, and Mindwave. The pH has gone up slightly to 8.0, but I'm not expecting Mindwave to change it much since it's sulfate-based.

This website I found has some interesting info. Apparently, most of Lake Tanganyika's carbonate comes from magnesium, not calcium. In fact, Malawi has more calcium, but lower pH and gH. It seems like magnesium carbonate is what gives Tanganyika its alkalinity. Plus, Tanganyika has way more potassium, sodium, and chloride than Malawi.

Since Mindwave won't change the pH, I think I need something that'll dose carbonates. I'm guessing I'll want more magnesium carbonates than calcium. Should I also add some salts to boost the potassium, sodium, and chloride levels? Any suggestions on products that can help me with this?

It's barely within the EU limit, but that doesn't exactly fill me with confidence. The World Health Organisation says 50ppm is safe for most people, but they do advise against it for pregnant women and young children - which makes me wonder just how safe it really is.

angelica wrote: ↑Fri May 02, 2025 3:15 am I think it's worth considering a balanced approach. For me, using an inert substrate and adding rift lake salts is the way to go. This way, you have complete control over the water parameters and don't have to worry about large water changes causing issues.

I've had my share of frustrations with Seachem products. They seem to want you to buy a whole range of products, which can get expensive. And let's be honest, who wants to do complex calculations every time you do a water change? I learned the hard way when I bought their Equilibrium product for a specific tank. I soon realized I also needed pH Up and pH Down, and working out the ratios was a nightmare. I ended up ditching it all and switching to mineflake salts, which have been a game-changer. I simply add the same amount to every bucket, and my water parameters are always spot on.

I also had issues with the Equilibrium product making my water cloudy, despite their claims that it would dissolve completely. Needless to say, I won't be using their products again anytime soon.

As for pH, I think it's overrated. If you get your GH and KH right, your pH will automatically fall into a suitable range. The actual value doesn't matter as much as people think.

I've been looking into nitrate levels in tap water and I think there's a distinction to be made between what our aquarium tests measure and what professional water authorities consider. I recall a member explaining this to me a few years ago, but unfortunately, the details have slipped my mind.

I did come across an article from Cornell University that might shed some light on this. According to the article, nitrate levels in drinking water can be measured in terms of either the amount of nitrogen present or the amount of nitrogen and oxygen combined. In the US, the federal standard for nitrate in drinking water is 10 milligrams per liter of nitrate-N, or 45 mg/l of nitrate-NO3 when oxygen is included in the measurement. Typically, nitrate levels only refer to the amount of nitrogen present, so the standard is usually 10 mg/l.

I'm not sure how this applies to the UK, but essjay might be able to provide some insight. I also found it interesting that the article mentions the usual standard being 10 mg/l, which is significantly lower than the 50ppm limit mentioned earlier.