Maintaining ph with a very low kh...?

[Bardot]

I have a lowish tech planted tank, use EI ferts and Glut. The ph comes out of my tap at 7.2 but the kh is less than 1 so this 7.2 does not hold for very long. Despite having a large amount of crushed coral in my filter I am still finding my ph dropping below 6 by the end of the week and as such am having to do smaller more regular water changes than my usual 50% to avoid ph shock.
My question is, would any of the EI ferts be contributing to the ph drop? I have 2 other smaller planted tanks, both have coral in their filters but I add no ferts and whilst the ph drops in these tanks it is not by a significant amount and I can still do 50% wc's without fear of ph shock. Or is there a product I can add to increase my kh without raising the ph....in other words just something to hold my 7.2 tap to around 6.6 ish for the week, have looked at JBL Aquadur....??
TIA.

 

[zozo]

I wouldn't worry so much about the ph, getting it stable without large fluctuations is much more important.. A ph of 8 isn't bad nor dangerous, plants maybe grow a little bit slower.. kh and ph are closely interactive i don't know for sure but i think any stuff changing kh value has affect on ph.. Most common stuff used is sodium bicarbonate also known as kH+.. For sale at the LFS and many supermarkets.
http://www.advancedaquarist.com/2002/6/chemistry

In my low tech situation i got about kh6 and my ph stabelizes steady at 8.5 where i get 7.5 from the tap.. And this all is still acceptable as long as it stays steady. And i still have plants growing at a steady pace even low tech plants have the capacity to addapt to low co2 concentrations.

It is because of my early days in aquarium keeping decades ago for many years where i never ever measured anything other than temperature and general water hardness. Did everything else on common sence and visual input.. And i never had any major problems.. That's why i do not worry so much today.. Even still today i also monitor my low tech parameters regularly out of curriosity and interest. And over the years gathered Paper ph test strips, drop test, permanent meters and pocket meters and i have not 2 giving the excact same value.. Beats me and can't tell you wich one is most accurate, i will never know, actualy don't want to know my tanks tell i do not realy need to know.. As long it is in a acceptable and stable range. I can understand and probably if i didn't have all those years of positive expernience without measuring a thing.. I probably would worry too..

The worries start when the measuring starts and oftenly clouds what you realy see. It converts a low tech tank in a high tech brain fart..

That said, the general consensus tells us, you should up your kh a bit to stop the fluctuations in ph.. Do it gradualy and do not worry to much if it raises your ph as well.. See where it stablelizes at an acceptable value and keep it like that. Do not fidlle around to much with those parameters.. You might end up from bad to worse

 

[rebel]

None of the EI salts should be contributing to the kh drop.

Plants will absorb kh a little though. Organic acids from organic breakdown can use up kh.

Remove the coral from your filter and crush it before returning it to the filter.