Backyard Aquaponics
A place to discuss aquaponics

Can someone please clarify how to read my new refractometer?

I am new to this and not sure.

on the calibrations it has 2 sides. one says d 20/20 and that reading is 1.007 of the salt in my tank.

the other side of % , from 1 - 100 reads 10 of the salt I have in.

So my question, is the % saying 10, 1% or 10%. Have i put in too much salt. The fish are doing OK but some plants are not doing well.

Thanks,

The left scale is a measure of specific gravity... the right hand scale is a measure of salinty.. in ppt...

So yes, with a spcific gravity reading of 1.007... your salinity is 10ppt.... no wonder your plants are struggling...

Most plants wont cope with more than 6ppt... and straberries, cucumbers, snow peas (and some others)... 3ppt...

10ppt is the suggested level for a salt bath for diseased fish.... most disease problems don't require more than 6ppt....

Do an immediate 50% water change... or sucessive daily water changes ... to bring your salinity back to at least 3-5ppt...

Many thanks for this and I have now changed some of the water and will test and do more in the morning.

Now I have another question that I am confused about.

I know salt does not evaporate from the water as it goes down, but I have not put salt in the tank for months, and all during this winter it has rained and added to the water, as well as now I top up the water with rain water as it evaporates. I would think that would lower the salt content?

Another problem I think I have is that the tap water here in Mandurah has a Ph of 8. That seems to high?
I can mix in rain water (with a Ph - 6) for now, but I will run out of rain water. I have a bag of shell grit in the tank. Does that work to balance both high and low Ph?

( seems there is always more to learn, and fun.)

Thanks for your help.

Linda

Hi Linda,
The shell grit is to stop Ph from plummeting down.
Personally I would remove it and just keep an eye on Ph, generally Ph takes a long time to go down. If you add Seasol and chelated iron powder your system should be fine (chelated iron enables plants to uptake nutrients when Ph is high). If your Ph drops to much you can put in a VERY SMALL AMOUNT of bricks lime which will bring it back up.
Fish don't like Ph to low so don't get to hung up on high Ph.
8 is fairly standard Ph for Perth water, filling with rainwater is a good idea.
Yes I would have thought that rain flooding system over winter would lower your salt content / level.
Finally thanks for asking the refractometer question as I was wondering how to read mine to.

Many thanks,

I have changed some water and salt is coming down.

Thanks also for your comment re refractometer reading, I thought I was being rather silly for not knowing.

Unless the water actually overflows, the added rainwater will just replace the water that evaporates or traspijjfgjhdfgates (goes out through leaves) so your salt levels should stay the same.

Having said that, we tasted some celery after salting, and it was so salty that we couldn't eat it. I seem to remember a health conscious aunty having celery salt, which I now presume is either celery made from salt, or salt made from celery.

Either way, all this means regardless of what I said first about salt levels staying the same, there is some stuff to suggest it can change in at least one direction, so I might be wrong about the other direction.

It's probably best to disregard this post all together, but apart from the word "traspijjfgjhdfgates" in the first paraghraph, that first bit is correct.

Celery salt is health conscious? I have it for flavour.. ingredients: Salt (68%), Celery seed (23%), rice flour, red capsicum, herbs and spice, vegetable oil..

I did read somewhere that tank water will lose about 1ppt per month to the plants..

As you said Bull, celery will take on the salt. As my system runs around 2-3ppt my celery is def a bit salty - mind you, I kinda like it. Bit of a salt fiend thou I must add..

I'm a fan of salty plums, (salt cured plums) but this was not very nice at all. Way too strong.

The aunt was only as health conscious as the last magazine said to be.

You know the kind of thing, "take the three day cheese detox diet to get rid of last weeks string bean detox diet residues".

For breakfast she ate vitamin pills on toast with her lactose free black carob coffee substitute

Can a refractometer read anything other than salt. Like nitrites etc?

Ha Ha - we have had this salty plum discussion a long long time ago Bull...do you remember? I love them little salty buggers too.



-as far as I know they only measure salinity..and some do temp aswel

Yeah of course I remember the only other person earth (who isn't family or someone I already know) who seems to like them