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Transition from Tap water to remineralised RO

Marios

Member
Joined
14 Sep 2021
Messages
49
Location
Cyprus
Hi all,

I don't know if all the information that will provide below are necessary but I will go ahead and provide them anyway, just to be safe.

Aquarium Dimensions
Width: 140 cm
Depth: 40 cm
Height 30 cm
Volume: 168L (Due to the large amount of wood used, I believe it to be around 150L, including the filters' volume capacity)

Equipment
1x JBL filter e1502, with purigen, connected with Aquario Neo Flow Pipes
1x JBL filter e902, with purigen, connected with Aquario Neo Flow Pipes
Eheim Skim 350
Inline heater set at 24c
Co2 art system with inline diffuser and additional camozzi needle valve.
Light: Chihiros WRGB2, currently set at 24% intensity and photoperiod of 7 and a half hours including of the ramp up of 30 mins and ramp down of 30 mins.
Jebao 4.1 wifi pump

Water Parameters
dKH: 15-16
dGH: 24-25
Ph (degassed tank water): 8.5
TDS: around 500

Fertilisation
I used to dose according to Clive's EI using salts, however due to the difficulty in getting Potassium Nitrate, as it is considered hazardous in Cyprus, I switched to APT EI which according to my dosage (3ml daily) and calculations it gives me the following weekly nutrients:

K: 14 ppm
NO3: 11.7 ppm
PO4: 3.82 ppm
Mg: 1 ppm
Fe: 0.41 ppm
+ trace elements

Also adding some additional Fe from Easylife Carbo (0.4 ppm), which as I've read has some more chelates, and I also add some liquid carbon.

Transition to remineralised RO

For quite some time, I was thinking of transitioning to softer water, for various reasons such as iron issues, fish that prefer softer water, limescale build up, grow some waters that prefer softer water etc. So I've recently purchased an inexpensive RO system to test it, before I commit and buy a more expensive one. It has the membrane, a fine filter and a carbon filter; there is no resin filter.

I have connected it to our garden water supply, which is an underground water source and the output TDS comes at 29ppm. (See Q1 and Q2 below)

I was planning to use tap water and RO mixture, to get to a desired GH and KH but then I decided that since I will be using the RO, it is better if I control what exactly goes into my aquarium water, so I went ahead and ordered yesterday MgSO4, CaCl2 and KHCO3.

I will slowly do the transition by doing small daily water changes of 10% with tap water (until the salts arrive from abroad), until I reach a desirable dKH and then continue with my normal weekly 50% water changes. (See Q3 and Q4 below)

Q1: Is there something that I need to worry about in using underground water after it has passed through the RO system, provided that the filters are changed regularly?

Q2: How do I know that the filters need changing? Do I assume that if the TDS increases then it is time to change them? And if so, should I replace them all or just one at time and see if that brings the TDS back to 29?

Q3: My targeted water parameters would be 1dKH and 6dGH with a 3:1 ratio of Ca:Mg. Would that be ok for the reasons provided above or do you suggest something different?

Q4 While I am doing the slow transition from tap to RO, should I be monitoring the pH as well? My current Ph drop is 1.1 with let's say 10bps and it starts around 3 hours before lights on. Will I need to adjust the rate and/or the injection period before lights on or does the KH drop not affect the amount of CO2 being injected in the water?

Q5: Is there something else that I should be aware of or take into consideration?


Many thanks for any assistance and for the time taken to read my post.
Marios
 
Q4 While I am doing the slow transition from tap to RO, should I be monitoring the pH as well? My current Ph drop is 1.1 with let's say 10bps and it starts around 3 hours before lights on. Will I need to adjust the rate and/or the injection period before lights on or does the KH drop not affect the amount of CO2 being injected in the water?

Your inject rate should not change, it will only be your starting and ending ph that will move on the scale. Co2 amount remain the same. So if you already have your 1.1 ph drop, it should remain de same after you lower you kh.
 
Your inject rate should not change, it will only be your starting and ending ph that will move on the scale. Co2 amount remain the same. So if you already have your 1.1 ph drop, it should remain de same after you lower you kh.
Many thanks. Is it also safe to assume that the 3 hours period from Co2 on to lights on should remain the same?
 
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