Variable water hardness

[Midas]

I just thought that I would post to mention something I have come across, not sure if will help anyone or not.

Has anyone ever noticed large variations in the carbonate hardness (KH) in their local water supply? When I first started fish keeping here in Palmy using filtered tap water I discovered that this was occuring.

I noticed that something was up when I was having problems keeping the pH stable in my tank. At the time I was carrying out bi-weekly 33% water changes and I noticed that some fornights the pH would be stable and other weeks it would drop significantly (from ~7.5 down as far as ~6). At this point in time I was new to the science and consulted the LFS for clues to what could be happening. They told me to change more water and clean my tank more throughly as it was because of fish waste etc building up. At this stage I was carrying out what I thought to be quite a thorough cleaning regime (including 33% water changes bi weekly on a fairly sparsely populated tank) and thought if I have to do more that this fish keeping thing is maybe a bit too much work.

After some revision of water chemistry and the purchase of a water hardness test kit I found the main reason I was having problems. I found that on some days the tap water would have a KH of about 100 ppm (pH ~8) and some days it would only be about 30ppm (pH ~7.5). If I did any number of water changes in a row with the softer of the two water supplies, the pH would start to drop after few days, due to normal aquarium life. So to fix the pH problems I was having, I chose to increase the KH of the water by adding sodium bicarbonate. Problem solved.

Still, it was a bit of a mystery why the water would be ok on some days and too soft for my needs on others. That was until I contacted the local council and asked about the water supply. As it turns out in Palmy there are two water supplies. One is from bore water (KH ~100ppm; pH ~8) and the other softer water comes from the water treatment plant which treats water from a catchment (KH ~30ppm; pH ~7.5). Depending where you are in the city you get either one or the other. However, in some locations you will get bore water one day and treated water the next, depending on the water demand at any particular time. We just happened to live in one of these locations that gets both.

[Benny]

this doesnt really answer your questin but-

when I was last up in wet pets there was a big sign on the wall saying DO NOT USE MANAWATU TAPWATER FOR YOUR AQUAIRUM or something like that. hahahaha I dont have that problem here!

[Midas]

All they are getting at with that sign is not to use it as it comes out of the tap, they recommend to filter it or something like that. They use Manawatu tap water themselves, they just filter it first. They are in an area of Palmy that always gets the harder water, so they didn't have the problem I had.

[Benny]

oh yeah...

[Caryl]

The water varies from region to region. Here in Blenheim we had no problems until the council decided the pH was too acid as it was eating the pipes (pH 6.8) so they now pour tons of lime and caustic soda into the town supply. A number of people are now having algae problems they never had before and I have had reports of dead pond fish after a water change.

Picton have to let water sit or use water conditioners (or agers) to get rid of the chlorine.

The most successful fish breeder we had in our club lived in Renwick and had bore water.

I don't know how aquarists find Nelson water (you can eat their tap water it has so much rubbish in it!).

[Midas]

oh yeah...

Yeah!

[Benny]

i suppose the water out of the tap is brown thats why wet pets uses a RO system for thier tanks

[Midas]

The water in PN is quite good really (its not brown). Seems a lot better than what Caryl mentioned in some other areas.

I have sample test information from the PN city council and the quality parameters for both the bore water and treated stuff are good. Nothing in there to cause concern at all for fish keeping, once its dechlorinated that is. Levels of heavy metals etc are low (<0.0005ppm), nitates are low (<0.1 ppm), phosphates are low (0.03ppm) and no chloramine.

Wet Pets do not use RO for the bulk of their water. They just put it through an activated carbon filter (a larger version of the house hold water filters) and then use it. So it can't be that bad. The only problem I had is that some days it was too soft and other days it was ok. All I have to do is work out which days its soft if I'm doing a water change and add sodium bicarbonate.

As an aside, what do other people use to increase the general hardness and alkalinity of their water if they need to? (e.g. for rain water or RO water users?). I have heard that Calicum hydroxide and even sodium hydroxide (!!!) can be used to increase pH, but these seem a bit harsh to me. Especially sodium hydroxide, which I have seen for sale as an aquarium water pH adjuster. I tend not to trust shop brought alkalinity reageants, especially when they don't say what is in them and charge the earth for what could be just a weak sodium bicarbonate solution. Has anyone tried mixing say Calcium chloride and sodium bicarbonate in low concentarions to increase both general and carbonate hardness of water?

[Rob]

For pH adjustments (up) I use Sodium bicarbonate - just a box of Pams baking soda from the super market.

For hardness adjustments - long term I'll add crushed shell or limestone bits to the tank/filter (need to be a little carefull that you don't over do it), for short term adjustments I'll use epsom salts (as permanent hardness is not only calcium based, but also magnesium) - epsom salts being magnesium sulphate.

[Warren]

You asked for it...

I use RO water exclusively in all may tanks. The fishroom has a continuous trickle of RO water entering the central filter sump. The excess overflows down the drain. Every 30 minutes, a dosing pump adds the following:

1. Sodium Bicarbonate

2. Calcium Chloride

3. Magnesium Sulphate

4. Potassium Sulphate

5. Sulphuric Acid

The 4 salts and the acid are premixed with water and stored in 25L tanks. The dosing pump adds a few drops of each to the sump every 30 minutes. The acid is added at the opposite end of the sump. This allows it to mix in ionically without reacting with the salts. This keeps a stable pH of 6.8 a KH of 30ppm and a GH of 60ppm. I get away with such soft water due to the continuous water change / dosing process. I keep mainly South American Cichlids and Tetras and they seem to like the soft water. They certainly spawn lots.

The inside display tanks, I add the same relative level of salts during a water change. The daily fertiliser dose contains the correct balance of salts to ensure stable pH of 6.8 all the time. It may fluctuate a little on a daily basis between doses, but it will not be more than 0.2ppm. The fish don't seem to care. Water changes are 50% one per week. I have levels marked on the tanks so I know how much to take out. I then know how much salt to add during the refilling process. Filling take about 1 hour (600L of water), and the salt mix is added from 3 containers using gravity feed. The hoses have a tap to adjust the flow so it take about 1 hour to add all the salt mix.

The above salts represent the most dominant salts present in natural waterways of South America. I got the information about the natural waterways from a book called the Optimum Aquarium. Unfortunately this book is no longer in print. It was written by the Dupla guys, who actually went to South America and measured the water parameters of many of the streams and rivers. It is the best book I've ever seen for the serious fishkeeper. I no longer have the book (it was borrowed), but would like to buy it from anyone who has a copy they do not want any more. I think it is worth a bar of gold! Anyway, back to the salts. They are mixed to as closely represent the compounds found in nature. It seems to work, - the fish are very strong and happy.

Water out for pH adjusters sold in Pet Shops. If they do not have the ingredients printed on the outside, they probably contain Phosphate based salts. These are very good a producing large quantities of algae. Look for products that do not contain any Phosphate.

The best and cheapest KH buffer seems to be Sodium Bicarbonate or Baking Soda as it is more commonly known. Dupla sells a KH buffer for about $20 that treats about 250L of water and raises the KH by 15ppm. I suspect it is Sodium Bicarbonate or something very similar. $20 will buy about 8kg of Sodium Bicarbonate from your local pool shop. This will last most aquarists about 2-3 years. Likewise with the GH buffers, most are available in bulk (like 2-4kg's) from the pool shop or industrial chemical supplier for less than it costs to treat your tank once. I don't mean to upset the retailers, but there are limits to what people with more than 20 tanks can afford. I go through 4kg of sodium bicarbonate in a year and 2-3kg of the other salts in the same time. I could not afford to buy these quantities retail without shutting down some tanks.

I suppose I should mention why I use RO water. Our lovely tap water has too much phosphate - about 8ppm too much. Everything else about it is pretty much perfect, - no chlorine, pH near 7.0 KH about 50ppm and GH about 90ppm, no Nitrate, Nitrite or Ammonia.

[Midas]

Sounds like an awesome setup Warren.

Just wondering what your secret is to be able to gavity feed 600L of water? Seems like a lot of water to hold at a level some where above the tank. Where do you position your 3 (200L?) containers and how do you fill these?

When I have a bigger tank I was thinking of using a sump to hold the water after it has been treated and then find some kind of pump to fill the tank at a decent flow rate.

[Warren]

Only the 20L of salt mix is gravity fed. The 600L comes from a 2000L outside storage tank and is pumped and preheated by a phase controlled 8kW heater element. This regulates the ouput temperature to 26'C ±0.5'C.

[Midas]

That sounds more like it, thought you must have had tanks in the ceiling or something.

What knid of tank do you use for your 2000L reservoir? Just a standard plastic moulded one? or do you have to be careful of what they make it of in case it releases undesirable chemicals?

[Warren]

I use ex-soap tanks from the local tanery. I've washed them out very thoroughly and joined 2 together. I use 2 more as coldwater ponds.

[Midas]

sounds like a good idea

Also, while we are on the topic, what would you recommend as a pump for a flow of about 200-400 l/hr at a head of about 2-3 metres? Are the garden pond type ones any good, or are there better deals at specilist comercial pump dealers?

[Warren]

Any submersable aquarium or pond pump will usually do. The cheaper ones are usually noisier and don't last very long, but this is not so important as this pump will only get intermittent use and will probably live outside. You will probably need a 600-800L per hour pump with a zero head. Just check the side of the box the pump is in, or the info leaflet inside for the pump curves. Pick the flow rate you want and match it to the head. It will show which pump in the range to choose if its not the one you picked up.

[Midas]

I have looked at pond pumps in LFS's and been matching up the curves, I was just wondering how much you are paying for a fully sumersible unit, being all plastic etc. Do you think that it would be worth while to get better pump from a comercial pump dealer that would still do the job but is not submersible? (e.g. put a tap/ outlet on the reservoir and plumb it up to there)

[Warren]

I only buy comercial units. I get them at trade with a small discount through my work. I have a 5000L/hour sumps pump (Cost $225.00 4 years ago) and a couple of 22000L/hour Sump Pumps ($305.00ea 2 years ago). The 22000 L/hour pumps are not rated for 100% duty, but have been running 24/7 for the last 2 years. They are Grunfos which seem to amoung the best you can get in NZ. You get a lot more pump for your $$ when you buy a comercial one but the problem is they are usually much bigger (>5000L/hour) and use more power (>100 Watts). This certainly adds up. A pump if running at full capacity 24/7 will usually use between 5 and 8 times its purchase price every year in power. This is not so for smaller pumps which use a lot less and larger pumps use a lot more.

[Midas]

Thanks for that I'll have a look around at whats available.

Depending on what filtration systems and filling options I go for I may need one or two decent size pumps. I'll have to size up things that you mentioned like running costs, capital outlay, amount of time in operation etc.

An engineering project to work on.