Hiya - I'm a n00b with a 440 L planted tank. My kH keeps dropping - I'm bringing it back up by adding Sera mineral salt with the weekly water change.

I understand this is normal for a planted tank, it's the plants consuming the minerals?

Can someone suggest a cheaper alternative to the Sera product? If I knew what mineral salts are needed I'm sure I could obtain the raw materials and mix my own batch.

-Si

I have been growing plants for many years and have never used it yet. What are you trying to achieve?

Yes it is normal as the plants use calcium, magnesium etc as they grow.

Have a search for "poor mans dosing drops" for an example of DIY fertilisers. There is a hydroponics crowd called Stocker who I use for my fertiliser supplies. Here's a link to them:

http://www.hydroponics.co.nz/

Baking soda will increase your Kh, very commonly used in marine tanks to increase kh. It wont however increase your Ca or Mg, do do this you need calcium chloride and magnesium chloride, the first can be purchased from a pool shop, the second from farm supply shop.

however, NEVER add any chemicals to a fish tank unless you can test for them, it is very easy to over dose.

IMO for normal planted tanks tap water usually has okay Kh etc levels, you are better off doing large water changes than dosing chemicals. If your parameters are dropping very fast I would be looking at other causes, like drift wood causing the water to go soft, or using rain water for water changes.

As an aside watch your Ph if you have low Kh, low Kh will let the Ph swing a lot, to test the Ph for swings, you have to test in the morning and evening, or two different times of day at least. Injecting CO2 into the water will also cause larger Ph swings.

Hamilton Water is really soft Skaffen, I've given up trying to keep the levels up, I chucked a few shells in my tank and that buffered it a bit.

What do you mean by realy soft? Christchurch water is 45ppm which by International standards is soft.

Im not sure how it compares with CCh water, I will do some tests on it tonight and let you know. I cant remember the exact results but when I first started I spent a fortune trying to bring it up to "suggested" levels but gave up in the end.

Ill test my semi planted community tank too and let you know what thats sitting at.

My Ph never varies much 6.5-7 so I've not really bothered to check gh/kh for ages.

Correct me if I'm wrong here but its only PH fluctuations that are really a problem to the run of the mill planted tank fish, (as long as you are doing regular water changes that is).

Correct.

A change of 6.5-7 is actually quite a bit change, the scale is logarithmic so a PH 4 is ten times more acidic than pH 5 and 100 times (10 times 10) more acidic than pH 6.

Using shell can be quite a good option because the amount it breaks down depends on the acidity, when you Ph drops it will break down faster and push your Ph back up. The problem is that you don't know what else is in the shell that is going to end up in your water.

Sorry, I just found this article, and I'm mixing up kH and gH:

http://www.drhelm.com/aquarium/chemistry.html

My pH is not swinging daily, despite the kH being so low, but Hamilton water is soft and acidic, so having low kH means my pH drops over time with several water changes. I've been keeping records and have observed this.

I've been looking at filshprofiles.com, and each fish has a recommended gH range (expressed in units of dH just to confuse noobs like me), e.g

http://www.fishprofiles.com/files/profiles/321.htm

This fits in with my observations - I've noticed my tiger barbs and siamese algae eaters start flashing a bit when the gH is below 4 dH. I add Sera mineral salt to get it back up to around 7 dH and the fish stop flashing. So I'm looking for a way to keep my gH at the recommended levels without having to buy the Sera product, which I'm sure is hugely marked up. If I could find the ingredients and ratios, I could make a poor man's mineral salt

simian & tHE cONCH, since the plants are consuming the minerals, surely they need them and have an optimal level as well?

Suphew, I have a couple of large bits of wood in the tank. How do they soften water, do they absorb the minerals? If so, hopefully they'll get saturated eventually?

purplecatfish, sorry but I think you're confusing ferts with minerals, I'm only asking about kH, pH and dH, oops, I mean gH Or does PMDD control gH as well?

Wood softens water by releasing tanins and humic acid (generally considered beneficial for South American fish) which react with the carbonates in your water lowering the pH and reducing its buffering capacity. If your pH keeps dropping a large amount that suggests more than just the action of the plants, although theoretically a lot of plants could release a lot of C02 at night which could become Carbonic Acid, consuming carbonates etc. and driving the pH down... but I would be suprised if the effect was that dramatic. Plants will have an optimum, but are generally pretty tolerant. I've never found it to be the limiting factor - light usually is. If you are worried about it I would add some coral rubble into your filter to act as a buffer.

I think it's probably a combination of a fair amount of wood, and the acidic and soft Ham water lowering the gH and pH over time due to water changes.

I'll give the coral a go. Thanks for the info, and sorry for spamming the forum with questions

Questions aren't spam

You can tell we are very upset with the questions because we dont answer

That's the whole point of the Forum Mate, after all replying to questions is better than actually working..which I should be doing

I own an accurate thermometer and that is the extent of my testing kits. I know what the Christchurch water supply is and that doing enough water changes will make the aquarium water very similar. I grow plants and keep fish that are happy to live in those conditions. Once you start chasing pH you will be doing it for ever. In my view it is a waste of time unless you wish to breed fish or keep plants and fish outside of "normal" parameters. Your plants and fish will generally tolerate a range of conditions better than they will tolerate wild swings caused by people "fiddling."

I own an accurate thermometer and that is the extent of my testing kits. I know what the Christchurch water supply is and that doing enough water changes will make the aquarium water very similar. I grow plants and keep fish that are happy to live in those conditions. Once you start chasing pH you will be doing it for ever. In my view it is a waste of time unless you wish to breed fish or keep plants and fish outside of "normal" parameters. Your plants and fish will generally tolerate a range of conditions better than they will tolerate wild swings caused by people "fiddling."

A very good point - stability is often more important than a particular pH / hardness value. Plants and fish do adapt gradually so if you do make changes, make them gradual.

purplecatfish, sorry but I think you're confusing ferts with minerals, I'm only asking about kH, pH and dH, oops, I mean gH Or does PMDD control gH as well?

The trace element mix in PMDD is an example of adding minerals that will add to the hardness of the water.

West Auckland tap water has a hardness of 0 or rarely 1 and I've found a few types of plants that just won't grow without added trace nutrients. I've also used scallop shells in a tank and they disolve over time adding to the hardness. And obviously with each water change I leached even more out.

A very good point - stability is often more important than a particular pH / hardness value.

This is so true, messing around with chemicals is the easiest way to stuff it all up. The shell method is slower and more gentle.

When you talk of a hardness of one do you mean ppm or degrees?

I'm talking degrees. Ham water comes out the tap reading 0 dH

Same as Titirangi, 0 degrees. Good old Waitakere Water Catchment Area surrounded by bush.

Shame hamilton water also smells so bad and its use is restricted. :lol: