Backyard Aquaponics
A place to discuss aquaponics

I reckon I am up to about 15 kg's in mine

Made use of my KH and GH test kits tonight - have had them for months but only used once .

Result is that the KH - as expected - is very low. Less than 1dkh (or 17.9ppm).

I lost some patience with the GH test and added multiple drops - result being that I only know it is somewhere between 7 and 11 (or thereabouts). Will recheck later.

Anyway - from the info on the site I quoted earlier - I calculate that I need to at 30 grams of calcium carbonate per 1000 litres for each dkh increase I want to achieve. (can somebody confirm my calculations here please). I estimate my system holds approx 1300 litres - meaning I need 39gms of calcium carbonate for each 1dkh increase. I reckon I want to increase to 10 - 15 dkh, meaning an addition of 390 - 585 gms of the stuff.

Of course I will want to do this a bit gradually (so as not to raise PH too quicly). Another problem is it will probably also increase the GH - so I will need to watch this.

Any comments.

BTW - PH is currently 6.4.

Have retested GH - it is 12dGH or 214ppm. This is quite high. I don't know if this presents a problem with raising the extremely low KH

VB, crash course follows;


GH is the measure of calcium and magnesium ions

KH is the measure of carbonate cations

If you put some epsom salts in then you will raise GH but not KH
If you put some Bi-carb (sodium) in you will rasie KH but not GH
If you put shells in (CaCO3) you will raise both as the carbonate is utilised.

SP are very tolerant fish..................

did you put lime in?

I have only ever put bi-carb in. I don't think there would be much trace of my original salt doses now - so I am not sure why the GH is so high, must just be the mains water. Will do a test on it when I can be botherred.

CaCO3 is calcium carbonate right? This is what I bought in podered from from the produce shop. I figured this would raise both.

PS - never added lime.

VB, do you have much trouble with solids in your fish tank? Do you scoop them out at all or do you find that they tend to be suspended in the water and go through to the growbed anyway..

I'm just wondering because I'm building a similar design to yours at the moment, but I'm thinking of extenting my intake down to near the bottom of the fish tank to remove more solids.

EB

In the early pictures and commentary of my redesigned sytem (around page 24 I think) I was yet to install the outer pipe in the fish tank (the one that goes over the 80mm standpipe). I had not done this at that stage because I had no 100mm pipe on hand. A couple of days later I bought some 100mm pipe and installed it. I simply cut crenelations in the bottom of the pipe and put the pipe straight over the top of the 80mm standpipe. The outer pipe (100mm pipe) is about 5-7cm taller than the inner pipe (80mm pipe installed in the drain). The effect is that the water flowing over the inner pipe and out to the grow-bed is drawn from the bottom of the tank and up between the outer and inner pipes. Because the outer pipe is not capped a siphon does not start which would cause the tank to empty altogether. Also, it should be noted that this outer pipe, although higher than the water level - is lower than the top of the tank. This means that if the space between the inner and outer pipes gets blocked - the water will simply rise and exit throught the insde pipe after overflowing over the outside pipe.

I guess I should take a new picture to show the tank as it now is.

Result of all this, and the whirlpool action of my tank, is that any poo ends up exiting the tank within no time of it coming out of a fishes bum. Similarly - any food which sinks and is not eaten gets removed to grow-bed very quickly (I use floating food).

This outer/inner pipe design is modelled of what Michael Ferrini has done.

PS - if you drilled a hole towards the bottom of the inner standpipe, this would also have the effect of drawing the wastes into the drain. The disadvantage of this - as opposed to having the outer pipe - is that if the pump stopped pumping from the sump to the fish tank, the fish tank would drain to the lowest level of the outlet pipe. In my case - this level is the same level as where it enters the grow-bed (about 30 or so cm lower than the water level that I currently maintain in the fish tank). Does that make sense.

Excellent...... thanks for the explanation VB, I must have missed it while scanning through the posts.. One other thing I may have missed as well, do you know roughly how often your water in the tank is changed out? ie pump capacity?

Hmmmmm, might well be the tap water. A mate of mine had that problem, and i know they do funky things to the water if they are going to pipe them along cement pipes.

do a kh and GH test on straight tap water.


yep caco3 is calcium carbonate, main component of shell grit and sea shells

salt won't show up as either

used the epsom salts (magnesium sulphate) as an example of how to raise gh with out KH only.

I estimate about once every hour at present (this is turnover of all water in the system - tank and sump). This of course would potentially double each time I double my grow-beds (provided I also increased my pump capacity or added another pump).

Fact is though - when I add my other beds - I will be using a larger tank and sump, so the turnover may be similar then. Once an hour does not present any problems I feel.

I'm not so sure about that Steve. When my system was salted - you may remember I did a GH test and gave up at about 30 drops.

well its not meant to!

I think we decided that because I had used sea rock salt that it may have contained minerals that increase GH.