Reducing High Alkalinity (KH), Feeding Stubborn Fish.

Question
Hi,
I have a 5 gallon tank. It's one of those types with the biofilter but I eventually had to retrofit it with a Tetra charcoal filter as well because well, the water here is pretty hard and clouds up easily, also the amount of mechanical filtration the biofilter provides was not enough. Anyway basically what I'm trying to accomplish is feeding the fish that eats from the middle of the tank somehow without having to overfeed the fish (because they miss a lot of the flakes as they sink). So I started with a vacation tablet type thing but when I installed it, it would not dissolve. So I reduced the general hardness in the tank with a water softener pillow, and the GH in the tank is actually lower than I want it. I did that because the airstones that I installed, well one of them I just rotate them out and restore them, they clog very rapidly. But the food tablet still does nothing, which I know is an indicator of high alkalinity, and when I test the water it is actually higher than 300. I suspect this is because I used to control the tanks pH with tablets or that there is just a lot of buffer in the water supply here. So anyway I've done mostly all I can think of to do and I have not used any buffering or pH tablets since the last couple water changes. Is there any way to actually balance the KH in the tank to make the food tablet dissolve? Is there any other way to feed the high fin tetras that are so stubborn about their eating habits?

Answer
Hi Corey,

Since you have a small tank, the best thing to do would be to cut your water with distilled water. You'll have to use your test kit to figure out the ratio, how much of the distilled water you'll need to cut your tap water with to get the results you desire. It might be that you need to go as high as 50/50, but if you're doing average 40% water changes a week (what I recommend for small tanks such as yours) then that means you only need 1 gallon of distilled water a week to do a 2 gallon water change, half with your own tap water and half with distilled water.

I'm not a big believer in "water softener pillows" and pH down powders and potions. It's easy to make soft water hard - you add carbonate hardness to the soft water (this could be as simple as adding some baking soda, sodium bicarbonate, or carbonate salts such as "Malawi salt mix"). But to make hard water soft, you need to take minerals away. The only way to do that is by cutting it with water that is "pure" and devoid of minerals. Any kind of pH down powders, drops, etc. will only work for a short time - eventually your pH, GH and KH will buoy back up. Hard water is actually very stable, and that is why many people (including myself) consider it to be a blessing in disguise:
http://www.wetwebmedia.com/FWsubwebindex/fwhardness.htm

Now, as to the vacation wafers. If you're talking about those white chaulky things that look like Plaster of Paris, forget these. They only pollute the tank - most fish don't want to eat them if they don't have to. If you want something the fish can pick at, try going to the grocery store and buying nori (roasted seaweed used for making sushi). I use a plastic clothespin and clip a strip of nori to it - the clothespin sinks and the nori sticks straight up where fish pick at it.

Bottom feeders like tablets and wafers, surface feeders like flakes, but for middle feeders there are slow sinking crumbles and pellets. Try, for example, Tetra Color Bits or Hikari Micro Pellets. Both of these foods sink slowly and are the perfect size for tetras. I hope that helps, take care!

Nicole