# Dosing of calcium?



## Conort2 (29 Oct 2020)

Hi,

I am currently running an aquarium with pure rainwater, due to Keeping some soft water fish and plant species. The tank is essentially high tech with co2 added and quite high light. I am dosing tropica specialised and profito at double the recommended dose, so still a lot leaner than EI. However I’ve noticed that neither of these fertilisers contain calcium. This never was a problem previously as my rock hard tap water was full of it. However I’d assume rainwater doesn’t contain any calcium whatsoever. 

Is this something I am going to need to add going forwards? Bare in mind I have species which like soft water so I wouldn’t want to raise the KH much if not at all if it’s not needed.

cheers

Conor


----------



## dw1305 (29 Oct 2020)

Hi all,


Conort2 said:


> However I’d assume rainwater doesn’t contain any calcium whatsoever.


It may contain some, dependent on the roof etc. My rain-water butts have some carbonate buffering, <"I assume from dust on the roof">. 


Conort2 said:


> This never was a problem previously as my rock hard tap water was full of it.


Can you just cut your rainwater with some tap? 

Because rainwater varies in conductivity during the year (lower in the winter) I use a conductivity datum rather than a set tap water addition. I just keep the tank water in the  80 - 140 microS range.  Our tap water is an aquifer supply and usually about 600 microS, so it is a pretty small amount of tap.

I'm assuming that most of the conductivity reading (in the cases of both rain and tap water) is from Ca++ and HCO3- ions.

cheers Darrel


----------



## Conort2 (29 Oct 2020)

dw1305 said:


> Can you just cut your rainwater with some tap?


I suppose I could add a splash to provide some calcium however it is rock hard so worried about it raising the tds too much. The rain water normally has a tds of around 40/50 time I add my ferts it’s more like 70/80. I’m trying to get my corydoras duplicareus to spawn which as you know are a black water species. Also have nannostomus mortenthaleri in with them and poecilocherax weitzmani which also like it very soft. I’m guessing all my tds at the moment is GH rather than KH so not sure how this affects soft water species like these, maybe I’m over thinking it?

cheers

Conor


----------



## dw1305 (30 Oct 2020)

Hi all,


Conort2 said:


> I suppose I could add a splash to provide some calcium however it is rock hard so worried about it raising the tds too much. The rain water normally has a tds of around 40/50 time I add my ferts it’s more like 70/80. I’m trying to get my corydoras duplicareus to spawn which as you know are a black water species. Also have nannostomus mortenthaleri in with them and poecilocherax weitzmani which also like it very soft. I’m guessing all my tds at the moment is GH rather than KH so not sure how this affects soft water species like these, maybe I’m over thinking it?


Because of the fish you are keeping (and what fish they are) I would just carry on with 100% rainwater. My guess is that you have some hardness (dGH/dKH) in your rainwater already. I would try heavy feeding with Blackworms to get the _Corydoras_ into spawning condition, and then a large cool rainwater change. I think you've got more chance of successful spawning in the winter, purely because the water will be softer (more rain, less dust).

cheers Darrel


----------



## Conort2 (30 Oct 2020)

I’ve started heavily feeding with freeze dried black worms so hopefully it will help, they also have a small group of good laser corydoras in with them. I have had no luck with either so far. Which is strange as I’ve found corydoras quite easy to spawn, normally a large cold water change does the trick. But no such luck with this bunch. 

I’ll stick with just the rain water for now then, what would I look out for to indicate a calcium deficiency on my Plants?

cheers

Conor


----------



## dw1305 (30 Oct 2020)

Hi all, 


Conort2 said:


> I look out for to indicate a calcium deficiency on my Plants?


I've only really ever seen it with _Vallisneria, _and then just as <"_failure to thrive">.  _It affects new growth (calcium isn't mobile in the plant).

cheers Darrel


----------

