Problems with exact idip

[cambag]

Good evening,

I noticed that my exact idip it has some problems.

I use idip to monitor my reef water values.

For some parameters, readings are completely out of order.

For example

Calcium 248 ppm, 410 measured by reagents kit (red sea and salifert)

KH 5.8, 8.5 measured by reagents kit (red sea and salifert)

PH. 3, 8.5 measured by reagents kit (red sea and salifert)

No3 Low, 1.5 mg/l measured by Hanna photometer

PO4 low, 0.05 mg/l measured by Hanna photometer

Can you help me to understand why these differences?

Exist a way to calibrate my device?

Thanks a lot for your support
G.