Water analysis

[Corwin]

I just bought 6in1 water analysis strips (for aquariums) to test my tap water + nutrients.

The results are :

Cl2 : 0 mg/l
pH : 6.8
GH : 8°d (Total hardness - calcium and Magnesium salts)
KH : 10°d (Carbonates hardness - bicarbonates)
NO2 : off the scale
NO3 : off the scale

So the pH is too high (I don't really know about KH and GH)

Would it be ok to add some rain water to get a pH of 6?

[King_of_orchid_growing:)]

The aquarium hobby is another one of my hobbies. I used to test for all this stuff for freshwater and saltwater aquariums. First off, the film strip tests are accurate, but they're not precise. A lot of more experienced aquarium hobbyists use titration tests which are much more precise but more complicated to use. There are also the expensive meters that only give a quick sample of what the readings are. The meters are precise, but they're too precise for the reason I mentioned about them.

KH is carbonate hardness. This measures the amount of dissolved calcium carbonate in the water. dKH is degrees of Karbonate (Carbonate) Hardness.

GH is general hardness. This measures the hardness of water in respect to all the other minerals in it.

The carbonates and other minerals are what's kicking the pH up. A pH of 6.8 is closer to neutral. A pH of around 5 or under is considered acidic. A pH of 8 or higher is considered alkaline.

Nitrates (NO3) and Nitrites (NO2) are by-products of the breaking down of Ammonia (NH3). This is part of the nitrogen cycle. Where ammonia is converted into nitrites, nitrites are converted into nitrates, and nitrates are converted into nitrogen gases.

In the case of tropical fish aquariums, we want a low nitrite and nitrate reading and a zero ammonia reading, because these compounds are toxic to fish.

In the case of plants, they're better equipped to handle nitrogenous compounds and utilize them in the aid of photosynthesis.

Depending on what orchids you grow, some of them will not tolerate a high level of dissolved minerals and salts (i.e. Disa, Pleurothallis, Lepanthes, Pabstia etc.). That's where the KH and GH come into play as factors in the testing of your water.

[King_of_orchid_growing:)]

BTW, a pH of 7.0 is considered neutral.

[buckie]

In general if you are drinking the water with no side effects, then it is good enough for your plants.

Warren

[Corwin]

Originally Posted by King_of_orchid_growing:)

BTW, a pH of 7.0 is considered neutral.

Isn't a pH between 5.5 and 6.5 considered better for orchids?

[Ray]

Yeah, but 6.8 isn't that bad. Certainly nothing to worry about.

I have to disagree with Warren's overly-general (in mt opinion) comment, though. When I lived in Kentucky, where we had liquid limestone known locally as "water" , it tasted great! I dare you to be a great phrag grower with it though.

[harrywitmore]

Originally Posted by Ray

Yeah, but 6.8 isn't that bad. Certainly nothing to worry about.

I have to disagree with Warren's overly-general (in mt opinion) comment, though. When I lived in Kentucky, where we had liquid limestone known locally as "water" , it tasted great! I dare you to be a great phrag grower with it though.

I would have to agree with Ray. My well water is some of the best I have had but orchids have never thrived for me and anything that gets misted with it develops a white scale. Since my new passion are Pleurothallids I can say from first hand experience that they don't like my well water.

[Corwin]

Thanks a lot for all the info!

I did a bit of research on the web... I found that page : http://www.thekrib.com/Plants/CO2/khgh.html
So it mean that 8°d GH(142.4 ppm) is between soft and medium hard

I redid the tests (to be sure) and the KH seems to be above 10 but I don't know how important that value is.

So is my tap water is alright for orchids?


(I want to do everything right from the start so, as i'm pretty insecure about the whole stuff, I keep asking questions. Hope you don't mind)

[King_of_orchid_growing:)]

It's fine for orchids that ARE NOT in the Pleurothallis Alliance, the pseudobulbless species of orchids from the Maxillaria Alliance, and Disas.

The dissolved salts and minerals in the water are too high for most Pleurothallis (i.e. Acronia, Rubiella, Ancipitia, Dracontia, etc.), Platystele, Masdevallias, Lepanthes, Lepanthopsis, Stelis, Trisetella, Dryadella, and Draculas. Over time, the leaves will drop without warning.

I've never grown Disas, but they can die from massive damage from leaf tip burn due to high concentrations of dissolved salts and minerals. According to all the sites I've read on them (I'm about to get a Disa soon).

Pabstia jugosa, a Maxillaria relative WILL ABSOLUTELY NOT TOLERATE a high dissolved salt and mineral content in water. I stress this because I grew them before and wiped them out by using tap water. I didn't know this at the time. I was told the concentration of dissolved minerals and salts it could handle, and it was very, very low (I forgot the exact number, but it wasn't 142.4 ppm, it was closer to 0.8 ppm I think).

Unfortunately I've never had the need to measure the GH of saltwater, so I can't go too much into this.

But to give you an idea of what 8 dKH is, saltwater in a marine aquarium must have a carbonate hardness of 8 dKH - 12 dKH maintained in order for the calcareous algae and reef building corals to produce calcium carbonate and calcium bicarbonate skeletal matrices (simply put, the coral animal through processes which is not quite understood makes a calcium based rock home for it to live in). In other words, a water with 8 dKH is hard water.

Now using freshwater fish as a reference for illustrating water hardness... Tetras (i.e. neon tetras, cardinal tetras) like soft water. They die prematurely if kept in hard water over a period of time. The water they like is preferrably 0 dKH and 0 GH.

[King_of_orchid_growing:)]

A quick word on the pH of water. It fluctuates within a certain range on a daily basis. This has something to do with the oxygen and hydrogen ratios in water, and other factors.